President Donald Trump plans to sign a compromise border security measure in conjunction with declaring a national emergency to secure funding for a border wall, according to Senate Majority Leader Mitch McConnell.

Speaking on the Senate floor on Thursday, McConnell sought to reassure lawmakers unsure of the President's position before taking a vote on the plan, which falls short of providing the $5 billion in border wall funding Trump had demanded.

“He has indicated he is prepared to sign the bill. He will also be issuing a national emergency declaration at the same time,” McConnell said. “I've indicated to him that I'm going to support the national emergency declaration. So for all of my colleagues, the President will sign the bill. We will be voting on it shortly.”

McConnell's abrupt announcement on Thursday that Trump would sign the spending package – ahead of any official word from the White House on the President's position – came after a day of consternation among Republican lawmakers and administration officials about whether the President would sign the bill.

The President's only public message was a midday tweet indicating he was still mulling the final text of the bill with his team at the White House. Even after McConnell's announcement, the White House was scrambling to make Trump's intentions official.

“President Trump will sign the government funding bill, and as he has stated before, he will also take other executive action – including a national emergency – to ensure we stop the national security and humanitarian crisis at the border,” press secretary Sarah Sanders wrote in a statement 25 minutes after McConnell spoke.

Concern over the government funding measure's contents extended to the White House, where aides spent all morning trying to digest the details of the 1,100-page bill and flag potential snags both to the President and to Capitol Hill. In briefings about the bill, the President expressed concern that something might be found buried in the bill after he signed it, leading to embarrassment.

Amid the wrangling, many of the President's senior advisers stressed he should sign the package to avoid another government shutdown, which they said would damage him politically. They said signing a national emergency declaration or some other type of executive action would blunt whatever blowback he received from conservatives.

Lawmakers were set to begin voting on Thursday afternoon. Many expressed hope – even prayers – the President would ultimately approve it.

“We'd like to know it's a bill the President is going to sign. Hopefully they will let us know,” said Sen. John Thune, the second-ranking GOP leader as he left a Republican conference lunch where the issue was discussed at length.

Others Republicans said they were still parsing the legislative text before committing to supporting the plan.

Earlier this week, Trump had signalled to advisers and allies he was inclined to sign the bipartisan deal to avoid another government shutdown, and would use executive action to attempt securing additional border wall dollars.

To appease the President, aides and some Republican lawmakers have cast the smaller figure, around $1.3 billion, as a down payment that will eventually lead to new wall construction.

Follow N1 via mobile apps for Android | iPhone/iPad | Windows| and social media on Twitter | Facebook.