WASHINGTON (Reuters) - U.S. Secretary of State nominee Mike Pompeo promised on Thursday he would be willing to break from President Donald Trump if necessary, saying he would take a tough line with Russia and that he wanted to “fix” the Iran nuclear deal.

Pompeo, who is currently director of the Central Intelligence Agency, blamed tensions between Moscow and Washington on Russia’s “bad behavior” and said he would support more U.S. sanctions against Russia.

“(Russian President) Vladimir Putin has not yet received the message sufficiently,” Pompeo told the Senate Foreign Relations Committee during a relatively smooth five-hour-long confirmation hearing.

He said Russia’s push into Ukraine and other countries needed to be curbed. “We need to push back in each place and in every vector,” Pompeo said. “We need to make sure that Vladimir Putin doesn’t succeed in what he believes his ultimate goal is.”

Critics, including some in Trump’s own Republican Party, have accused the president of taking too soft a line on the Russian president. Trump has denied that - and has been strongly critical in recent days of Moscow’s backing of Syrian President Bashar al-Assad - but he has also talked of wanting better relations with Putin.

Trump nominated Pompeo to become the country's top diplomat on March 13 after firing Rex Tillerson. Tillerson, a former chief executive of Exxon MobilXOM.N, had a rocky relationship with Trump in just over a year in the job.

The start of Pompeo’s hearing was disrupted by protesters chanting: “No Pompeo, no more war.” Another shouted that the CIA director was no diplomat.

DEMOCRATIC PRAISE

While Pompeo faced pointed questions from Democrats - including about his continued opposition to gay marriage and his associations with anti-Muslim organizations - he was also complimented. Democratic Senator Ben Cardin praised Pompeo’s concise answers. Senator Chris Coons said he was “confident” Pompeo would be a strong advocate for diplomats.

Pompeo will likely need Democratic support to be approved by the committee because one Republican member, Senator Rand Paul, has announced his opposition. Senate rules allow a vote in the full Senate even if the panel does not approve the nomination, but that has never happened with a secretary of state.

Senator Bob Corker, the panel’s Republican chairman, said he hoped it would vote on Pompeo on April 23, with a confirmation vote in the full Senate shortly afterward. At the end of the hearing, Corker said Pompeo had his “avid” support.

Senator Robert Menendez, the panel’s top Democrat, said he would make his final decision after reviewing Pompeo’s testimony and answers to written questions. He said he had not seen enough evidence of Pompeo’s independence.

“I think he is someone who will execute what the president wants even if he is in disagreement,” Menendez said.

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As a Republican congressman, Pompeo was a strong opponent of the 2015 nuclear pact between Iran and six world powers reached under Democratic President Barack Obama, which lifted sanctions on Iran in exchange for curbs on Tehran’s nuclear program.

Trump has delivered an ultimatum that Britain, France and Germany must agree to “fix the terrible flaws of the Iran nuclear deal” or he will refuse to extend the sanctions relief by a May 12 deadline.

Pompeo said he favored a “fix” and believed Iran was not “racing” to develop a nuclear weapon before the deal was finalized, and that he did not expect it would do so if the deal were to fall apart.

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Defense Secretary Jim Mattis said in a separate congressional hearing on Thursday that he also believed the agreement should be fixed and the administration was working with allies to address its flaws.

TIES TO TRUMP

Pompeo was pressed repeatedly on whether Trump spoke to him about the investigation looking into alleged Russian meddling in the 2016 U.S. presidential election.

Pompeo acknowledged he had been interviewed by Special Counsel Robert Mueller, whose federal probe includes looking into whether there was collusion between Moscow and Trump’s campaign. He declined to discuss details.

U.S. intelligence agencies concluded Russia interfered in the campaign to boost Trump. Moscow denies doing so and Trump has denied collusion by his campaign.

Trump developed a warm relationship with Pompeo during White House meetings over the first year of his presidency and believes Pompeo shares more of his world view than Tillerson.

Pompeo was questioned repeatedly over whether he would act independently and stand up to Trump. There has been rapid turnover among senior administration officials, with the president souring rapidly on those who disagreed with him.

Pompeo promised he would be his own man as secretary of state, saying his relationship with Trump meant, “I was able to persuade him” when he headed the CIA.

Menendez said Trump’s “erratic approach” to foreign policy had confused allies and emboldened adversaries. “Will you stand up to President Trump and advise him differently when he is wrong? Or will you be a yes man?” Menendez asked.

Pompeo promised to rebuild the State Department, which has been gutted by the departure of senior diplomats and often found itself sidelined by the White House.

A reorganization and hiring freeze initiated by Tillerson left the rank and file demoralized.

Pompeo said he would work quickly in his new role to fill vacant positions and promised to spend money allocated by Congress for State Department programs.