WASHINGTON — Republicans critical of U.S.-Iran nuclear talks contend President Barack Obama is so keen for a deal that he is ignoring Tehran’s moves to expand its influence across the Middle East.

GOP hawks maintain that Obama wants so much to burnish his legacy by negotiating an agreement to restrain Iran from becoming a nuclear-armed state that he is not pushing back against Iranian activities in Iraq, Yemen, Syria, Lebanon and Bahrain.

Secretary of State John Kerry has pushed back against lawmakers, including some who insist that the nuclear negotiations have hamstrung U.S. policy decisions in the region.

“Yes, Iran’s influence has spread at this moment and we are deeply concerned about it,” Kerry said at one congressional hearing. “But if you’re concerned about it now, think of what happens ... if they had a nuclear weapon.”

Republicans point to the activities of Iran, the dominant Shiite force in the Middle East, in these countries:

• Iraq: Iran-backed militias are fighting alongside Iraqi forces to retake Tikrit, a Sunni stronghold seized by Islamic State militants. Army Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, says the U.S. worries that the militiamen, who are Shiite, eventually might turn against Sunni and Kurdish Iraqis, further destabilizing the country.

• Yemen: The Obama administration had cited Yemen as a success in the fight against terrorism. But Houthi rebels, backed by Iran, seized the capital, Sanaa, from a U.S.-backed leader who supported American drone strikes against suspected al-Qaida figures. Nick Rasmussen, who directs the National Counter Terrorism Center, recently told the Senate Intelligence Committee that Yemen’s American-funded army failed to oppose advancing Houthi rebels, and that the government’s collapse surprised the U.S.

• Syria: Iran supports Syrian President Bashar Assad, who has waged an unrelenting campaign of bloodshed and starvation against his own people.

Among the Democrats countering the GOP refrain, Sen. Tim Kaine, D-Va., says he shares the concern about Iran’s involvement but “this is not about turning Iran from an enemy into a friend. This is whether an enemy has a nuclear weapon or doesn’t. The administration is very realistic. If there is a good nuclear deal, we still have to confront the adventurism of Iran beyond its borders.”