Sens. Susan Collins and Tom Udall have teamed up on the Senate version of legislation disapproving of President Trump’s border security national emergency.

Udall, a Democrat from New Mexico and an appropriator, said the resolution to terminate the national emergency isn’t really even about the proposed border wall itself, saying on the Senate floor this is a matter of “standing up for the Constitution.”

He said the declaration was “an end run around Congress’s power to appropriate, plain and simple.”

Collins, a Republican from Maine, followed Udall on the Senate floor, where she cited writings from both Alexander Hamilton and James Madison in the Federalist Papers, including when Madison described the power of the purse being reserved for the legislature as “the most complete and effectual weapon with which any constitution can arm the immediate representatives of the people.”

“The question before us is not whether to support or oppose the wall. It is not whether to support or oppose President Trump,” Collins said. “Rather, it is this: do we want the executive branch, now or in the future, to hold the power that the founders deliberately entrusted to Congress?”

Udall said Sens. Lisa Murkowski of Maine and Jeanne Shaheen of New Hampshire were also on board to help lead the joint resolution. All four of those senators are members of the Appropriations Committee.

The House voted Tuesday to pass the joint resolution through that chamber, and Senate Majority Leader Mitch McConnell of Kentucky has indicated that under the expedited procedures available under the National Emergencies Act, it should be on the Senate floor before the next scheduled recess the week of St. Patrick’s Day.

In addition to Collins and Murkowski, Thom Tillis of North Carolina has expressed support. And more GOP supporters are expected, meaning the joint resolution should easily clear the Senate with a simple majority.

At least some of the Republican critics of the national emergency, including some of the 13 House Republicans who voted for passage in that chamber, have said they support Trump’s objectives when it comes to enhancing border security, including with more physical barricades.

But like Collins, other members of the GOP in both chambers have expressed constitutional concerns about the separation of powers, especially when it comes to preserving the power of the purse as the Trump administration seeks to reallocate billions of federal funds.

Speaker later in the day on the Senate floor, Tennessee GOP Sen. Lamar Alexander did not announce how he would vote on the joint resolution, but he encouraged White House lawyers to back away from the national emergency.

Of course, President Donald Trump has already announced his intention to veto the measure, and House Republicans expect that they will have enough votes to uphold that veto.