President Trump may soon face an open rebellion from Republican senators who are trying to place additional sanctions on the Russian government and its allies. Even as Mr. Trump pushes for a peace agreement between Russia and Ukraine, Congress is ready to attack President Putin directly. 

An overwhelming majority of senators — 81 to be exact — have already signed on to a Russia sanctions bill that would impose tariffs on nations that buy certain energy products from the Russian federation, among other additional measures. If the legislation were passed by Congress, they would have a veto-proof majority supporting the bill, meaning the sanctions could go into effect even without the president’s support.

The Senate majority leader, John Thune, though, seems reluctant to buck the White House on the issue even with the numbers in his favor.

Mr. Trump has been trying to play peacemaker between Mr. Putin and President Zelensky since returning to the White House in January, though those efforts have yielded no results so far. Russia reneged on an agreement for a cease-fire back in March, and Mr. Putin walked back his offer to meet with Mr. Zelensky in Turkey earlier this month. 

On Sunday, the potential for a peace deal likely hit yet another setback after the Russian military launched hundreds of missiles and drones into Ukraine, leaving at least a dozen people dead and many more injured. Earlier the same day, the chief of Russia’s air defenses claimed that Mr. Putin’s presidential helicopter was at the “epicenter” of a Ukrainian drone attack that occurred while the Russian president was visiting the Kursk region this past week, according to the Kyiv Independent. 

Last week, Mr. Trump spoke with both Messrs. Putin and Zelensky, as well as other European leaders, for several hours to try to set up the framework for peace talks. The president said the negotiations were set to begin “immediately,” though no public dealmaking has been announced and Mr. Putin has so far shown little interest in pursuing any sort of peace agreement. 

Mr. Zelensky said after that call that his government was “ready for a full and unconditional cease-fire,” though if the Russians would not comply, then they should face “stronger sanctions.” Republicans in Congress seem to agree, despite Mr. Trump’s insistence that America should be a neutral arbiter during the negotiations. 

Senator Graham, a Republican, and Senator Blumenthal, a Democrat, in early April introduced the legislation aimed at sanctioning both the Russian government and its trading partners. At the time of its introduction, the bill had 50 co-sponsors, though that quickly grew to 81. 

“The sanctions against Russia require tariffs on countries who purchase Russian oil, gas, uranium and other products. They are hard hitting for a reason,” Messrs. Graham and Blumenthal said at the time the sanctions bill was introduced. “The dominating view in the United States Senate is that Russia is the aggressor, and that this horrific war and Putin’s aggression must end now and be deterred in the future.”

It’s now clear that Mr. Thune may soon have to side with the vast majority of his Republican and Democratic colleagues to push this sanctions bill forward if progress is not made in the current round of peace talks. Speaking on the Senate floor on Thursday, Mr. Thune said he was prepared to put the Graham–Blumenthal bill on the floor if the Russian president does not get serious about peace. 

“The Senate stands ready to act. Thanks to the dogged work of Senator Graham, we have bipartisan legislation — co-sponsored by 80 of my colleagues — to impose additional economic sanctions and tariffs on Russia,” Mr. Thune said. “If Russia is not willing to engage in serious diplomacy, the Senate will work with the Trump administration to consider additional sanctions to force Putin to start negotiating.”

The Trump administration, though, seems to have no interest in the bill that Mr. Graham has put together. Secretary Rubio — a longtime Russia hawk during his time in the Senate who is now trying to cobble together a peace deal — told members of Congress this week that a sanctions bill at this time would be unwise given how delicate potential peace talks will be. 

“He wants to preserve as long as he possibly can the opportunity to influence both sides towards peace,” Mr. Rubio told members of the Senate Foreign Relations Committee last week, talking about Mr. Trump’s desire to act as a mediator. 

The secretary of state said that while sanctions are not now being considered by the White House, it may look into such actions in the future. “I think there’s a chance of getting something done. And if you do that, you can also make it much worse. But there could be a time when that’s going to happen,” Mr. Rubio said.