I would think that a president challenging the will of congress would cause congress to vote differently out of principle but am curious if this is true.
Throughout history, what is the percentage increase or decrease in congressmen and women who vote for a bill after it has been vetoed?
cross-asked on politics.stackexchange here
I don't think it makes a lot of sense to compare numbers, because they are completely different kinds of votes, with different thresholds. But we can look at some historic trends.
First off, veto overrides are quite rare. It has to be an issue both houses of Congress have 2/3rds support for, yet the POTUS doesn't want. If its clear that level of support is unobtainable, then there no reason to hold the vote, and the veto will just be left to stand.
Secondly its an implicit rebuke to the sitting President. Generally the POTUS is also the figurehead of his party, so many folks who might otherwise support the law in question would be loathe to vote to override their own leader's veto. Conversely, many who might be lukewarm on the law might be quite happy to vote to override the other party's leader.
The very first veto in US history didn't happen for more than 50 years. In that case the POTUS in question was a lame duck ascended VP who had campaigned against his own party in the election. It was another 4 presidents later before there was a second veto override.
To be fair, vetoes themselves were much rarer back then as well.
The most recent veto override was in late 2016 of the Obama administration. Again, this was while he was technically a lame duck. The leader of his party running for President at the time was Hillary Clinton, so there wasn't that much of a downside to the party in voting against the President on this one. That was Obama's only veto override.
His predecessor GWB had 4 veto overrides. All of them came from the 110th Congress, in which the Democrats (barely) held both chambers, and all but one of them came in his last year in office.
