The House on Monday voted to beef up stimulus checks set to go out to American households in the coming weeks from $600 to $2,000. The chamber acted swiftly after President Trump demanded the larger payments last week, but passage of the measure is uncertain because Senate Republicans have not unified behind the idea.

On Sunday, Trump signed into law a $900 billion emergency relief package that included $600 checks. His advisers had advocated for those payments, but Trump later called the check size “measly” and demanded it be increased. After he signed the law, he pledged to continue pushing for the larger payments, something many Democrats also support.

Forty-four Republicans joined the vast majority of Democrats on Monday in approving the bill on a 275-to-134 vote — narrowly clearing the two-thirds threshold it needed to pass. The measure’s fate is much less certain in the Senate, which is controlled by Republicans.

Approving stimulus checks of $2,000 would cost $464 billion, the Joint Committee on Taxation said Monday. That would be in addition to the $900 billion package Trump signed into law Sunday. Congressional Republicans had sought to keep the total price tag under $1 trillion, but that was before Trump began a fierce effort in the past week to make the stimulus payments larger.

One reason for the growing support is the weakening economy, coupled with the spreading pandemic, which has led to more people seeking unemployment benefits and turning to food banks for help.

Since Trump first demanded the larger checks on Dec. 22, House Speaker Nancy Pelosi (D-Calif.) and other Democrats have tried to push the idea into law. They have ignored his other complaints about the new spending package, however, particularly his calls for reductions in foreign aid and environmental programs.

“It’s not exactly what we would put on the floor if Republicans were in control,” said Rep. Tom Reed (R-N.Y.), who supported the larger checks. “But I think it recognizes the fact that [Pelosi is] the speaker and as a Democratic speaker, they’re going to have an input as to what that package is going to look like in regards to the terms and conditions of the direct checks. I’m willing to take half a loaf, and I think the president recognizes that.”

Monday’s vote took place after House Republican leaders blocked an attempt last week to pass the larger checks by unanimous consent in the House. The measure now goes to the Senate, and it is uncertain whether Majority Leader Mitch McConnell (R-Ky.) will move to consider it in the closing days of the current Congress. Some Senate Republicans are supportive of larger checks, though. The idea has been championed by Sen. Josh Hawley (Mo.), and Sen. Marco Rubio (Fla.) said he backed larger payments as well.

“I am concerned about the debt, but working families have been hurt badly by the pandemic,” Rubio wrote on Twitter on Monday. “This is why I supported $600 direct payments to working families & if given the chance will vote to increase the amount.”

Still, a number of Republicans have come out against the larger checks. Rep. Kevin Brady (R-Texas), the top Republican on the House Ways and Means Committee, said the money would be better used by giving it directly to small businesses to increase hiring.

“Will this stimulate our local economies?” Brady said on the House floor. “Not a lot. What we know is that much of this extra [money] will go to pay down credit card debt, or savings, or even make new purchases online at Walmart, Best Buy, or Amazon.”

But Trump’s support for the larger checks has only grown each day. In a statement Sunday, Trump said the Senate would “start the process for a vote that increases checks to $2,000, repeals [liability protections for tech companies], and starts an investigation into voter fraud.”

McConnell has not signaled precisely what he will do with the measure once it is sent over from the House. A McConnell spokesman declined to comment Monday.

Senate Minority Leader Charles E. Schumer (D-N.Y.) said Sunday that he would attempt to pass the bill in the Senate himself as soon as Tuesday morning, but any one senator could block the measure from proceeding. McConnell could seek to package the larger checks with other Trump demands, but that would probably generate Democratic objections and prevent a vote before the new Congress is seated on Jan. 3.

After the House voted to increase stimulus checks to $2,000, Senate Majority Leader Mitch McConnell (Ky.) blocked an initial attempt for approval on Dec. 29. (The Washington Post)

In March, Congress passed the Cares Act, a $2 trillion measure that included a round of $1,200 stimulus checks for more than 100 million Americans. The initiative had mixed results, according to several studies. Many people used the money to pay rent or buy groceries. But others saved the money or used it to pay down debt.

Congress has designed the stimulus checks so that most people would qualify for them — but not everyone. Americans with income up to $75,000 would qualify for the full amount, but people who earn more would receive smaller checks.