The federal government didn't offer any sort of plan for compensated emancipation to the slave states, because the slave states had too much control and influence in the federal government before 1860 for the federal government to take any sort of anti slavery action.
After the election of 1860, when the slave states clearly saw they had lost their disproportionate influence on the federal government, most of then seceded and formed the CSA, and fighting soon broke out against the southern Rebellion. During the course of the conflict, it became a war to end slavery.
However, there was a government propose for compensated emancipation in four states, that was not acted upon.
Abolitionists demanded the immediate abolition of slavery - thus they were called abolitionists.
But abolitionists were a minority in the Republican Party and in the anti slavery movement and in the population of the free states and territories.
The political platform of the Republican Party in 1860 didn't demand the immediate abolition of slavery, or offer a five year plan to gradually abolish slavery, or a ten year plan, or anything. If I remember correctly Lincoln hoped that the anti slavery measues of the Republican Party would cause slavery to gradually decline and vanish in fifty years. But fity years was not some sort of Republican deadline.
The Republican Party considered that abolishing slavery where it already existed in the slave states would be very difficult and probably unconstitutional. Instead the Republican Party had a platform to make things better for the inhabitants of the free states, which involved among other things doing everything possible to limit the expansion of slavery into new territory.
So what the pr o slavery politicians in the slave states feared the Republicans would do was something like this:
Since Congress controlled the District of Columbia, a Republican majority in Congress could abolish slavery in the District of Columbia. The southern states had insisted on having the permanent capital of the USA in slave territory so that southern members of Congress & government officials could bring their slaves to the capital to serve them without worrying that the slaves might gain their freedom as had been the case when the capital had been in New York and in Philadelphia.
If free state politicians controlled the federal government, they could abolish the hated fugitive slave law requiring the citizens of free states to cooperate with hunters of escaped slaves.
If free state politicians controlled the federal government, they could restrict interstate commerce in slaves. The deep south states had declining slave populations as slaves died off faster than they had children, and the upper south states had surpluses of slaves, since slaves were bred faster than theY died off in the upper south. So the internal slave trade was big business, with the upper south selling its surplus crop of slaves to the lower south.
Since the federal government had the power to regulate interstate commerce, if free state politicians controlled the federal government they could restrict or abolish interstate trade in slaves. Then the upper south with be stuck with a surplus of slaves with drastically reduced values, and the lower south would face a declining slave supply unless they found a way to make their slaves reproduce faster.
If free state politicians controlled the federal government they would control the post office in the southern states. Up until 1860 southern politicians had made sure that only southern postmasters were appointed in the south and that they confiscated and destroyed any anti slavery pamphlets that were mailed to the south. But if free state politicians controlled the post office they could appoint northern postmasters to southern post offices who would deliver anti slavery pamphlets, and possibly in time an antislavery group would form in the south and vote to abolish slavery.
If Free state politicians controlled the Federal government they could abolish slavery in the territories and refuse to admit any territory which had slavery as a state. Thus all new states admitted when free state controlled the federal government would likely be free states, and the number of free states and their proportion relative to slave states would increase.
Furthermore, many slave state politicians wanted to invade and conquer parts of Mexico, South America, and the Caribbean and reintroduce slavery there to increase the number of slave states in the union. Free state politicians had opposed such plans and as Free states gain more power in congress their opposition would be stronger in the future. So many slave state politicians wanted to leave the USA and form their own country to conquer much of Latin America and spread slavery.
The slave states were losing their ability to control the federal government, prevent it from taking any slavery measure, and make take pro slavery measures.
Each state had two senators in the US senate.
But in the house of representatives the number of representatives a state had was proportional to its population. To be precise, in each state, free or slave, each free person was counted as one person when deciding how many representatives the state had. But each slave in a slave state was counted as two thirds of a person when deciding how many representatives the state had. This was a compromise between those who wanted to count the slaves in the population and those who didn't.
So if a free state and a slave state had the same populations of free persons, the slaves in the slave state would give it extra representatives in the House of Representatives and extra political power in the federal government.
But over time the population of free persons in the free states increased much faster than the population of free persons in the slave states, where opportunities were much more limited. Immigrants from foreign countries settled int he free states where there wre more opportunities much more often than in the slave states. And the number of slaves in the slave states increased, but not nearly as fast as the number of free persons increased in the free states.
So it soon became easy to predict that in the future the free states would have a majority of representatives in the House of Representatives.
But each state had two senators in the
senate. If the number of slave states equaled or exceeded the number of free states, the slave states could have had equal votes or a majority in the Senate, enough to block any type of antislavery legislation passed by the House.
So in the Missouri Compromise of 1820 it was decided that in the future states would be admitted in pairs, with one slave state and one free state each time, so that the balance between slave states and free states in the Senate would be unchanged.
But in the late 1840s more free states than slave states were admitted to the Union. By the election in 1860, there were 33 states in the Union, 15 slave and 18 free. The slave states were falling farther and farther behind in the Senate.
The number of federal electors each state had was equal to its representatives and senators in congress. Thus by the election of 1860 it became impossible for the slave states to elect a president all by themselves. Slave state politicians had to cooperate with free state politicians to elect a president that they both approved of, or else be certain to loose the presidential election and have a president who wasn't favorable to the slave states.
For many decades most presidential candidates were favorable to the politically powerful slave states. They were either slave owning southern politicians themselves or they were free state politicians who were favorable to the continuation of slavery either by belief or by political expediency.
But with the growing anti slavery movement in the free states, and the declining political power of the slave states, free state politicians who favored slavery from conviction and/or from expediency were becoming rarer.
In the presidential election of 1860, Abraham Lincoln, the most anti slavery major candidate, received 180 votes in the electoral college, 28 more than the 152 necessary to win the election, while the other three candidates received a total of 123 votes in the electoral college. Lincoln received 0.5940 of the electoral college votes.
Nothing the slave state politicians could have done would have prevented Lincoln's election. But, perhaps hoping to make Lincoln's election more probable to force secession, the Democratic Party couldn't agree on a candidate and split into northern and southern groups who offered rival candidates, while there was a fourth party, the Constitutional Union Party, in the border states.
In any case, the election of 1860 showed that free state politicians could gain a majority in Congress and that someone could be elected president without even being on the ballot in 10 of the slave states, and while getting only a small part of the vote in the south.
Clearly the era of southern control or significant and disproportional influence on the federal government was ending. So in the eyes of many slave owning pro slavery slave state politicians the usefulness of the United States of America for them was ended in 1860 and they considered it time to either dissolve the union or withdraw from it and form a more slavery favoring country.
The Lincoln administratin did propose compensated emancipation in four states, Delaware, Maryland, Kentucky, and Missouri.
During the course of the Civil War, the Lincoln administration made the emancipation Proclamation, declaring, as a matter of military necessity, freedom for all the slaves in territories then in rebellion against the USA, and millions of slaves were freed in the later course of the war and when various parts of the south surrendered in 1865.
There were four slave states, Delaware, Maryland, Kentucky, and Missouri, that remained part of the USA during the War of Southern Treason, The slaves in those states remained slaves since they were not covered by the Emancipation Proclamation.
During the Slaveowner's Rebellion Lincoln offered plans for the gradual and compensated emancipation of slaves in the four border states to their state legislatures. But those legislatures, probably having great difficulty in agreeing, never accepted those offers.
Bills proposing an amendment to the constitution to abolish slavery were proposed in 1863 and 1864. The Amendment passed the Senate May, 1864, and finally passed the House of Representatives January 31,1865.
The Amendment was sent to the states for ratification. It was ratified by Illinois February I, 1865, and g was ratified by Georgia December 6, 1865, making the necessary 27 votes for the amendment to become part of the constitution. Thus teh slave owners in the four border states of Delaware, Maryland, Kentucky, and Missouri failed to get their legislatures to act fast enough to take advantage of Lincoln's proposals for compensated emancipation.