In what scenario is a presidential veto most likely to be upheld?

A presidential veto is most likely to be upheld when two-thirds of the legislature is of the President's party because that scenario indicates a strong alignment between the executive and legislative branches. If a substantial majority of legislators belong to the same party as the President, they are less likely to challenge the President's veto. This party unity often translates into shared policy goals and priorities, making it more difficult for opposing members of the legislature to gather the necessary two-thirds majority required to override the veto.

In circumstances where the President is in a second term, there may be less political pressure to appease certain factions, but this does not inherently guarantee that the veto will be upheld or overridden. Widespread bipartisan support for the legislation generally makes it more likely that legislators will unite to challenge a veto. Additionally, having support from the Supreme Court does not directly influence whether a veto is upheld, as the judicial branch does not play a role in the legislative process surrounding vetoes.