A group of senators, including some Republicans, pushed back on the agreement. President Donald Trump doubled down Monday on his decision to allow Russian diesel imports amid growing backlash, calling it the "right choice" and arguing that Europe has previously purchased energy products from Russia as well.

Trump said in a Monday morning social media post that the "European Union paid Russia 250 Billion Dollars for Energy" and added, "I made the right choice for the American People — ALWAYS, AMERICA FIRST!" Trump did not specify the period covered by $250 billion figure. Estimates from the Centre for Research on Energy and Clean Air tracking how much the EU has spent importing fossil fuels from Russia since the start of war with Ukraine roughly align with the figure Trump mentioned.

Trump's comments come after a small group of bipartisan senators came out against the Trump administration's plan to lift Russian oil sanctions and import a new supply amid spiking prices in the U.S. The senators, in a statement on Sunday, urged the administration to reverse its decision due to the ongoing war with Ukraine and ban on Russian energy imports. "The United States should not provide Putin with a financial lifeline while Russia continues to kill Ukrainian civilians. The Administration must immediately reverse course," the senators wrote in the statement.

Trump announced on Friday that he made a deal with Russian President Vladimir Putin to immediately import 300,000 tons of its diesel fuel, with a promise that millions more are coming.

The statement was signed by Republican Sens. Susan Collins, Thom Tillis, John Curtis and Lisa Murkowski as well as Democratic Sens.

Jeanne Shaheen, Richard Blumenthal and Ron Wyden. The senators also argued the move violates a 2022 law banning Russian energy imports and opens the door to allowing Russia to potentially benefit financially on its war against Ukraine.

"President Trump's decision to allow Russian diesel imports to the U.S. runs directly counter to that law.

The Administration has also failed to consult with Congress or submit any explanation to justify its decision as required by statute," the senators wrote in the statement.

In April 2022, Congress passed the Ending Importation of Russian Oil Act, banning imports of Russian energy products. While the law does allow the president to lift the ban under certain conditions, it requires a justification to Congress before doing so, which the senators argue did not happen.

Ukrainian President Volodymyr Zelenskyy sharply criticized the decision, too, saying in an interview with ABC News over the weekend that the deal amounts to an "obvious weakness."

"It plays into Russia’s hands -- allowing it to kill more, wage war for longer, have even less respect for America, and inflict even greater losses and damage on the world," he said. "We count on America's fair support for our defense of life, for our defense of people in Ukraine -- and on the United States having a correspondingly strong conversation with Russia.

A strong one, not a weak one." Trump's decision comes weeks after he signed the bipartisan Lindsey O. Graham Sanctioning Russia and Iran Act, which authorizes tariffs on countries that continue to purchase Russian oil. Now, some senators, such as Tillis, say Trump's recent action runs counter to the efforts in the legislation.

"I completely reject it," Tillis said on NBC’s "Meet The Press" on Sunday. "If President Trump wants to end the strain of energy supplies, number one, get things right in Iran, and number two, recognize that it was Vladimir Putin, not Zelenskyy, that started this war. And it's Vladimir Putin who owns the responsibility for energy prices to the extent that they come from that part of the world."

Tillis said the agreement to purchase Russian diesel is "essentially, I think, tarnishing Lindsey Graham's efforts to try and get those sanctions bill through." However, other Republicans are continuing to stand by Trump, including House Majority Whip Tom Emmer, who is a vocal supporter of Ukraine and previously voted to establish sanctions on Russia.

Emmer told ABC News' "This Week" co-anchor Jon Karl on Sunday that the deal was "another example of our president thinking out of the box" to address the American public's concerns about high oil and gas prices by importing fuel to the U.S. ahead of the midterm elections.

"He's listening to the American people, Jon. The American people are hurting because of this world market when it comes to diesel and fuel in general,” Emmer said.

Emmer also hailed the deal as another tactic in Trump's attempt to broker a peace deal between Russia and Ukraine. "I think this is just another step of trying to get that resolved," he said.