«What happens if Trump vetoes the resolution?
In the Senate, 67 votes would be needed to override his veto, meaning 20 Republicans would need to break with the president. As noted above, there are more than 20 Senate Republicans wary of this move. So it’s at least theoretically possible that the dam could break; the fissures run deeper than the typical issues on which only a handful of Republicans like Collins and Murkowski are considering a vote against the president. But not liking the emergency declaration and voting for a resolution that will stop it — and stoking Trump’s anger as many Republicans are gearing up for primaries in 2020 — are totally different things. It’s also not clear if McConnell is required to even hold a vote on the veto override.
The bill would also have to achieve a two-thirds majority in the House, which wouldn’t be easy. FiveThirtyEight has not done a formal whip count in the lower chamber. A two-thirds majority would require 288 votes — so 53 Republicans would have to join all the Democrats. Most Republicans in competitive districts lost in 2018, which means there are relatively few GOP representatives left who have to worry about electoral pressure. Earlier this year, amid the government shutdown, for instance, a bloc of about a dozen Republicans broke with Trump to back some Democratic measures to fund the government without wall money. So it’s not like all 197 House Republicans are Trump loyalists. But a dozen is a long way from the 53 GOP votes in the House to override his veto.»