WASHINGTON ― Sen. Lamar Alexander (R-Tenn.) strongly suggested on Thursday that he would not support President Donald Trump’s declaration of a national emergency to fund construction of a wall along the U.S.-Mexico border.

“I support what the president wants to do on border security, but I do not support the way he has been advised to do it,” Alexander said in a speech on the Senate floor. “It is unnecessary and unwise to turn a border crisis into a constitutional crisis.”

Trump declared a national emergency two weeks ago, after failing to convince Congress to give him more than $5 billion to build his promised border wall. The declaration would allow Trump to use money Congress specifically appropriated for military projects to begin wall construction.

Alexander’s opposition to the declaration would be significant. Three of his fellow Republicans have said they would join with Democrats and vote to disapprove of the declaration. Only four Republicans are needed to pass the measure, because Democrats control 47 seats, and the resolution requires a simple majority of 51 votes.

Alexander did not specifically say whether he would support the disapproval resolution. Instead, he urged the administration to take other funds Congress has authorized for Department of Defense drug interdiction efforts as well as the Treasury Department to build the proposed border wall.

“There is time for the president’s lawyers to take another look,” he said, calling the emergency declaration a “dangerous precedent” that future Democratic presidents could use to advance their agenda without congressional approval.

The Democratic-controlled House voted on Tuesday, largely along party lines, to block the president from redirecting military construction money to a border wall.

The Senate must vote on the disapproval resolution within the next two weeks, putting many GOP senators in an awkward spot, given the Trump administration’s threat earlier this week to veto the measure. A number of Senate Republicans expressed concern about the declaration during a conference lunch with Vice President Mike Pence on Tuesday.

However, even if the disapproval resolution passes in the Senate, it is unlikely to receive 67 votes in the upper chamber and a two-thirds majority in the House needed to override a presidential veto.

Sixteen states are currently suing the Trump administration over the emergency declaration, and Trump is likely to face additional challenges from the American Civil Liberties Union and a coalition of border property owners.