President Donald Trump’s declaration of a national emergency to fund his border wall has come under withering bipartisan criticism. Whether he’s able to hold off a congressional push to block the move will soon become clear.

House Democrats are expected to pass a formal resolution of disapproval of Trump’s declaration, which would then head to the Senate floor where only a simple majority is needed for passage.

Although many GOP senators criticized Trump for declaring a national emergency, few have said whether they would break with the president. Here are some of the crucial voters to keep an eye on — a collection of more centrist Republicans and GOP incumbents who could face tough reelection bids in 2020. If four Republicans join all Democrats, Trump could impose his first veto.

Opposition to Trump’s declaration of national emergency:

Mild Strong