President Trump said Thursday he's ready to issue the first veto of his administration if the Senate passes a resolution to overturn his national emergency declaration to build a border wall.

“A big National Emergency vote today by The United States Senate on Border Security & the Wall (which is already under major construction),” Trump tweeted Thursday morning. “I am prepared to veto, if necessary. The Southern Border is a National Security and Humanitarian Nightmare, but it can be easily fixed!”

A big National Emergency vote today by The United States Senate on Border Security & the Wall (which is already under major construction). I am prepared to veto, if necessary. The Southern Border is a National Security and Humanitarian Nightmare, but it can be easily fixed! — Donald J. Trump (@realDonaldTrump) March 14, 2019

On Wednesday, Trump rejected efforts from Senate Republicans to pass a compromise measure that would restrict the use of emergency powers in the future, in order to get Republicans to vote against a resolution opposing his border emergency. Trump's rejection prompted Republican Sen. Mike Lee of Utah, who was leading the compromise effort, to announce he would vote in favor of the resolution Thursday.

[Opinion: Pass both Nancy Pelosi's and Mike Lee's national emergency bills]

“For decades, Congress has been giving far too much legislative power to the executive branch. While there was attention on the issue I had hoped the ARTICLE ONE Act could begin to take that power back,” Lee said in a statement Wednesday after Trump told him he didn't support the compromise plan.

Republican senators expected to vote to overturn the national emergency declaration are Sens. Mike Lee, Susan Collins of Maine, Lisa Murkowski of Alaska, and Rand Paul of Kentucky. Other Republicans could also choose to back the resolution.

Trump declared a national emergency at the border after Congress failed to approve $5.7 billion for a border wall project. The declaration moves billions of dollars from the military construction budget to construct physical barriers on the border. Trump's move prompted a swift legal challenge from more than a dozen states, as well as rebuke from Democrats and some Republican lawmakers.