Donald Trump attempted to counter a simmering anti-Israel backlash in Congress and among his own Maga supporters on Tuesday by denying suggestions that he had been bounced into attacking Iran because Israel had already decided to do so.

Amid growing criticism among opponents and allies alike, Trump rebuffed claims that he had struck Iran only because Israel had forced his hand, a suspicion fueled by comments made by Marco Rubio, the secretary of state.

Asked whether Israel had pushed him into launching military action, Trump told reporters: “No. I might have forced their hand.

“We were having negotiations with these lunatics, and it was my opinion that they were going to attack first. They were going to attack. If we didn’t do it, they were going to attack first. I felt strongly about that.”

Senate Democrats reacted furiously after Rubio suggested on a visit to Capitol Hill that Saturday’s strikes were driven by the need to pre-empt Iranian retaliation against US interests in response to Israeli attacks that Washington knew was coming.

Rubio’s comments – made after a briefing conducted with the CIA director, John Ratcliffe, and Gen Dan Caine, chair of the US armed forces’ joint chiefs of staff – fueled suspicions from some on both the left and right of the political spectrum that Israel’s interests, rather than those of the US, dictated the decision to resort to open warfare.

“We knew that there was going to be an Israeli action,” he told reporters on Monday. “We knew that that would precipitate an attack against American forces, and we knew that if we didn’t pre-emptively go after them before they launched those attacks, we would suffer higher casualties.”

That rationale has provoked anger among Democrats, as well as segments of Donald Trump’s base, who see the attack on Iran – and specifically its timing – as at odds with his previously proclaimed “America first” foreign policy goals.

Democrats seized on Rubio’s explanation as grist for forthcoming votes on war powers resolutions, which have been brought before the Senate and House of Representatives this week to assert the constitutional principle that a president must consult Congress before waging war.

“We have to have a debate in the United States Senate on an authorization of military force,” Chris Murphy, a Democratic senator, said on Tuesday evening after he and other lawmakers received a classified briefing from Rubio and other top administration officials. He acknowledged that the resolution “will likely fail”, but said: “We shouldn’t be voting to proceed to other pieces of legislation until we get a debate on this deeply unpopular, immoral and illegal war with Iran.”

While the briefing was intended to update lawmakers on the conflict’s goals, many Democrats said the administration failed to articulate their objectives, raising concerns of the US getting bogged down in a conflict with Iran.

“When there’s no set plan, when you can’t hear day after day we’re going to do this, this, this and this, and these are the reasons why, you end up with an endless war. You end up with mission creep, you end up with all kinds of problems,” Chuck Schumer, the Senate minority leader, said.

Republican lawmakers generally backed Trump’s approach, arguing the president had removed from power a despotic regime with a long record of killing Americans in the Middle East.

“We have lost thousands of individuals over 47 years, and we haven’t done anything about it,” senator Markwayne Mullin said. “This threat was not going away. I don’t think anybody can argue that this regime needed to be removed.”

Growing concerns over Israel’s role in the White House decision to go to war could further change perceptions of the country’s relationship with the US, building on the criticism that has emerged following the long war in Gaza. Opinions polls have shown a sharp drop in support among Americans following the Israeli military offensive in Gaza, which has killed about 70,000 Palestinians and was launched in response to Hamas’s murderous October 2023 attack that slaughtered 1,200 people, mainly civilians, on the Israeli side.

Trump has provided fluid reasoning for why he ordered attacks last Saturday, in concert with Israeli strikes, one of which killed Iran’s most powerful figure, the supreme leader Ayatollah Ali Khamenei. He has also sent mixed signals about whether he is willing to deploy US forces in a “boots on the ground” capacity, a decision that would almost certainly further inflame domestic criticism.

In his initial statement on Saturday, he said the goal was to “ defend the American people by eliminating imminent threats from the Iranian regime”.

But some of the president’s most prominent social media influencers jumped on Rubio’s remarks to challenge that justification.

“Rubio’s comments are a record scratch moment,” wrote Mike Cernovich, a prominent pro-Trump social media influencer. “He said what most guessed was the case. That he said [this] out loud … is a sea change in foreign policy. There will be massive calls for a walk back.”

“So he’s flat out telling us that we’re in a war with Iran because Israel forced our hand,” posted Matt Walsh of the rightwing Daily Wire magazine. “This is basically the worst possible thing he could have said.”

Speaking on his War Room podcast, Steve Bannon, Trump’s former White House aide, said: “If we knew Israel would strike and Iran would retaliate against us, where was the coordination? We need a strategic explanation.”

The belief that the attack on Iran is primarily an Israeli interest has been compounded by the comments of Benjamin Netanyahu, Israel’s prime minister, who has visited Trump numerous times in recent months to press the case for action against Tehran’s theocracy, most recently last month.

“This coalition of forces allows us to do what I have yearned to do for 40 years: smite the terror regime hip and thigh,” he said on Sunday. “This is what I promised – and this is what we shall do.”

Referring to the first four US casualties of Iran’s retaliation against the strikes, the conservative journalist Megyn Kelly said on her online broadcast: “My own feeling is that no one should have to die for a foreign country.

“I don’t think those four service members died for the United States, I think they died for Iran or for Israel … this feels very much to me like it is clearly Israel’s war. It would explain perfectly why President Trump is having so much difficulty explaining why we are doing this.”