The Senate voted along party lines on Wednesday to take up Republicans’ $70 billion immigration crackdown bill, but several G.O.P. senators suggested they would not allow it to pass without new language barring President Trump from creating a fund to compensate his political allies.
The 53-to-46 vote began debate on legislation that was supposed to unite Republicans around Mr. Trump’s hard-line immigration enforcement agenda, but has instead become a flashpoint for clashes between the president and G.O.P. members of Congress just months before the midterm elections.
Before bringing it up, Republicans followed through on a decision they made late last month to jettison $1 billion in security funds for Mr. Trump’s ballroom and other White House renovations, which had drawn a mini-revolt within his party.
They were also discussing adding a provision that would block Mr. Trump from resurrecting the idea of creating a $1.8 billion fund to pay people who claim to have been victimized by the government, which the administration dropped this week after it came under withering attack from members of both parties.
The vote set the stage for a lengthy vote-a-thon on a range of issues that is expected to culminate on Thursday in Senate passage of the immigration enforcement bill, which Republicans are pushing through Congress using special procedures that shield it from a filibuster. To do so, they will need near unanimity to overcome united Democratic opposition.
Even after sworn testimony on Tuesday by Todd Blanche, the acting attorney general, that the administration was not now — or ever — moving forward with the fund, a significant bloc of Republican senators still wanted to codify that statement in the bill. Some of them said their votes for the measure, which funds Immigration and Customs Enforcement and Customs and Border Protection, were contingent on doing so.
It marked an unusual moment of proactive challenge to the president from Republican senators who have spent much of his second term simply falling in line behind him. Given that the legislation ultimately must be signed by Mr. Trump, it also set up a test of his willingness to stomach such pushback from Congress, or whether he would instead veto a measure to fund a centerpiece of his own agenda.
“We don’t want to oppose the president just for the sake of opposing the president,” said Senator Thom Tillis, Republican of North Carolina. But with one-third of Republican senators up for re-election in November, Mr. Tillis said there was simply no way to vote for the fund.
“The only way you can explain it, is explain that you got rid of it,” he said. “I feel like there are people advising the president as if there is no election in November.”
At the White House not long after the Senate began debating the bill, Mr. Trump cast doubt on whether he had truly abandoned the fund, telling reporters “I love it” and “it’s so important,” and saying he was unsure of its fate.
Democrats have promised to force votes on the fund, which was announced as part of a settlement Mr. Trump reached with the Internal Revenue Service last month, and a separate provision of that deal that shields the president, his family and businesses from audits.
The idea of the fund had generated wide resistance from Republicans, including some in the House and Senate who face tough re-election challenges in November. Some of the most vocal pushback came from Republican senators like Mr. Tillis who have little left to lose politically by crossing a vengeful president.
Mr. Tillis, who is not seeking re-election next year, said his vote to move ahead with the reconciliation bill was contingent on a commitment from Republican leaders that he would get a vote on an amendment that would permanently shut down what the administration had called its “weaponization” fund.
Senator Bill Cassidy, the Louisiana Republican who recently lost his primary to a Trump-backed challenger, also said Mr. Blanche’s statement had been a good start but was not sufficient, indicating that he might support a Democratic amendment to ban the fund, or introduce his own.
“You want to make sure something that’s just dead, not just mostly dead, you want to make sure it’s really dead, and I think we can make it really good,” he said.
Senator John Cornyn of Texas, another Republican who lost his primary to a Trump-backed challenger, also indicated that he would support codifying Mr. Blanche’s statement into law through legislation.
On Wednesday morning, Mr. Cornyn shared on social media an editorial from The Wall Street Journal that urged lawmakers to kill the fund once and for all, quoting a line that read: “The way to ensure the Trump retribution fund is more than mostly dead would be for Congress to put a stake through it.”
Robert Jimison contributed reporting.
