WASHINGTON — Just ahead of Tuesday's House vote on a resolution that would terminate President Donald Trump’s emergency declaration, there were fresh signs it could also pass the GOP-controlled Senate.

Sen. Lisa Murkowski of Alaska became the latest Republican to indicate that she'll likely vote for the resolution once it reaches the Senate.

"I want to make sure that the resolution of disapproval is exactly what I think it is, because if it is as I understand it to be, I will likely be supporting the resolution to disapprove of the action," Murkowski said, The Anchorage Daily News reported Friday.

The same day, Murkowski also told Anchorage TV station KTUU, “If it's what I have seen right now, I will support the resolution to disapprove."

Sen. Susan Collins, R-Maine, who’s up for re-election in 2020, has made similar statements about voting in favor of the resolution, though no Senate Republican has firmly committed to backing the measure.

Assuming all Democrats support the resolution, only four Republicans would need to defect for Democrats to secure the 51 votes needed to send it to the president’s desk.

Lawmakers may also be feeling outside pressure. More than 50 former national security officials from both parties sent a public letter to the Trump administration Monday arguing that there’s no evidence of a national emergency at the border.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

“Under no plausible assessment of the evidence is there a national emergency today that entitles the president to tap into funds appropriated for other purposes to build a wall at the southern border,” the ex-officials said in the letter, which was signed by veterans of multiple administrations, including former Clinton secretary of state Madeleine Albright, and former Obama defense secretary and GOP senator Chuck Hagel.

Former Obama homeland security secretary Jeh Johnson said in an interview with NBC’s “Meet the Press” on Sunday that he doesn’t think it was appropriate for the president to have declared a national emergency.

“That is intended for military construction in support of a war or a national emergency, historically, overseas. And so this is really, in my judgment, trying to fit a square peg in a round hole,” Johnson said. “Better to work with Congress and collectively come to the smartest, best solution.”

Freshman Rep. Max Rose, D-N.Y., wondered in an interview on MSNBC’s “Kasie DC” on Sunday why it took two years for Trump declare the emergency.

“What was happening for the first two years of his presidency, when his party literally had the keys to the castle?” Rose said. “No declaration of a state of emergency. But now it happens. And I believe the reason is because this is politics. It's politics at play. It's an opening salvo to Trump/Pence 2020, and that's what's wrong here.”

In declaring the emergency, Trump is expected to have access to $8 billion for the wall, including $3.6 billion in military construction from the Department of Defense.

The House Appropriations subcommittee that oversees military construction, chaired by Rep. Debbie Wasserman Schultz, D-Fla., is scheduled to hold a hearing Wednesday on Capitol Hill with top officials from the Army, Navy and Air Force to discuss how the national emergency will affect military construction and readiness.

The House will vote Tuesday on a resolution by Rep. Joaquin Castro, D-Texas, that as of Friday had around 227 co-sponsors, including one House Republican, more than the majority needed to pass.

House Majority Leader Steny Hoyer, D-Md., said at a press conference Monday evening with other House Democrats that he had recently visited the border.

"What I concluded: there is no crisis at the border. The issue tomorrow will be whether there is a crisis of our constitutional adherence," he said. "The issue will be whether or not the Congress of the United States will exercise the authority given to it under Article I of the Constitution or whether it will abdicate its responsibilities."

Speaker Nancy Pelosi, D-Calif., again urged GOP lawmakers to back the resolution.

"What the president is saying about the border is mythology, it is not reality," she said. "I know that our Republican colleagues care about the Constitution…I know that they would not want a president — Republican or Democrat — to usurp the powers of the institution of which we serve."

Under the National Emergencies Act of 1976, Congress has the ability to try to end an emergency status instituted by the president. Democrats in the House will have no problem passing the resolution given their 235-197 majority.

Once it passes the House, the measure will be sent to the Senate, where unlike most pieces of legislation, GOP leaders could not block it from reaching the floor. The federal law requires that the Senate take up the House-passed resolution within 18 days.

Administration aides have already made clear that Trump would veto any effort to interfere with his declaration.