DENVER — A spokesperson for Colorado Sen. Cory Gardner (R) said he hasn’t decided if he will vote against President Trump’s national emergency declaration.

The Democrat-led U.S. House passed a resolution on Tuesday night that blocks the president’s declaration. It passed 245-182, falling short of the two-thirds majority vote needed to override any presidential veto.

More than a dozen House Republicans voted in favor of the measure, while all representatives from Colorado voted along party lines.

Trump declared the emergency earlier this month to provide funding for a border wall with Mexico. The Republican-controlled U.S. Senate will decide next if they agree with a resolution that goes against the president.

Gardner’s vote could very well seal that measure’s fate. Three Republican Senators - Thom Tills of North Carolina, Susan Collins of Maine, and Lisa Murkowski of Alaska - have indicated they plan to vote with Democrats to approve the measure. Tillis and Collins, like Gardner, are up for re-election in 2020.

One more Republican could pass the measure, assuming all Senate Democrats approve.

In an interview with Colorado Public Radio one day prior to Trump’s announcement, Gardner seemed to have already made up his mind on an emergency declaration. He said then that he had personally told the president that he opposes it.

“I think Congress needs to do its job,” Gardner said to CPR.

Trump tweeted on Monday that he hopes Republican Senators avoid the Democrats’ “trap.”

The White House threatened a veto on the resolution in a statement issued earlier Tuesday.

The Senate has 18 days to vote.