DAVENPORT, Iowa — In the days since President Trump authorized the killing of a top Iranian leader, former vice president Joe Biden has made his extensive foreign policy experience a central part of his campaign pitch.

But even as he urges voters to consider his diplomatic credentials a month before the Iowa caucuses, he faces significant risks. Biden has overstated his initial opposition to the Iraq War in recent days. Some voters are asking about his ostensible missteps on the global stage. And Sen. Bernie Sanders (I-Vt.), an increasingly vociferous Biden opponent, is contrasting his own opposition to the Iraq War with Biden’s position.

During a just-concluded five-day bus tour across Iowa, Biden regularly touted his tenure as chairman of the Senate Foreign Relations Committee and his endorsement by former secretary of state John F. Kerry. He told voters that he had met most of the world’s leaders, casually mentioning his relationship with Israeli Prime Minister Benjamin Netanyahu, for example, and calling Netanyahu by his nickname “Bibi.”

He has told audiences that Barack Obama chose him to be his vice president for his foreign policy expertise. “Joe will handle that,” Biden quoted Obama as telling other officials in his administration. “He knows more about it than anybody. Work with Joe.”

In an effort to seize momentum on the issue, Biden’s campaign announced late Monday that he would deliver a statement Tuesday in New York on the rising tension between the United States and Iran. Aides said he will emphasize the need for the United States to regain “respected, responsible and dignified leadership” internationally, expanding on the arguments he has been making in Iowa — that Trump is recklessly endangering America’s position and Biden is best qualified to remedy that.

But at an event in Des Moines on Saturday night, one person raised what he called Biden’s foreign policy missteps — voting against the 1991 Persian Gulf War, then for the Iraq War; advising Obama against the raid that killed Osama bin Laden — and wondered aloud whether Biden was as sure-footed on foreign policy as he wanted caucusgoers to believe.

Biden responded with an answer that touched on everything from his Oval Office conversations with President George W. Bush to a private aside with Obama on the bin Laden raid.

Biden also said he opposed the Iraq War “from the very moment” it started, although the record suggests he supported it initially.

Part of Biden’s answer seemed to undercut his argument about how savvy he is on the international stage, since he said he had been misled by Bush about Iraq. “He looked me in the eye in the Oval Office and promised me all he wanted to do was get the authority to send the inspectors in,” Biden told the crowd in Des Moines.

But he said that although he had not been right on everything, he still was the candidate with the best foreign policy experience.

“It’s not to suggest I haven’t made mistakes in my career, but I will put my record against anyone in public life in terms of foreign policy,” Biden said to applause.

Sanders, for his part, has been restating his criticism of Biden’s 2002 vote in favor of the invasion of Iraq. Sanders has noted that he opposed the war in Vietnam, voted against the Iraq War, and is now against going to war against Iran, touting his consistency in this area as well as in others.

Former South Bend, Ind., mayor Peter Buttigieg and Sen. Amy Klobuchar (D-Minn.) have also said in recent days that the Iraq War was a mistake.

The Democratic primary race has not focused significantly on foreign policy until recently, instead revolving around issues of health care, income inequality, immigration, gun policy and other domestic matters.

But there have been signs that could be changing since the killing of Iranian Maj. Gen. Qasem Soleimani, an official whose death in an American drone strike has provoked a sharp response from Iran, including massive protests and Tehran’s withdrawal from a 2015 nuclear agreement.

Religious and political leaders in the Middle East have called for vengeance against the United States, and President Trump has tweeted that he would target Iranian cultural sites if Tehran targets Americans, further incensing Iranians.

Biden, who recently released a viral campaign ad that highlighted a moment in which world leaders laughed at Trump during a NATO summit reception, said the president’s tweetstorm was further evidence that Trump is bumbling on the international stage.

“Does anybody here think he has any notion of what the next step is?” he asked attendees at his final town hall of the weekend, in Davenport.

The issue highlights the dual nature of Biden’s long experience in Washington.

He often cites that experience as evidence that he knows how to get things done and that as president he would be able to return things to normal, or some version of it, following the disruptive and chaotic Trump presidency.

But his decades in government have also yielded moments that Biden has had to explain or apologize for, such as his handling of Clarence Thomas’s Supreme Court confirmation hearings and his spearheading of a crime bill opposed by many in the black community.

In the foreign policy arena, Biden’s role is also complicated by the House impeachment investigation of Trump and the potential for a Senate trial this month.

Beginning in 2014, Biden’s son Hunter served as a board member of a Ukrainian gas company at the same time that Biden, then vice president, was coordinating U.S. policy toward Ukraine.

Trump’s request to Ukraine that it investigate the role of the Bidens there was the trigger for the president’s impeachment by the House on allegations that he was abusing his power in an effort to hurt a political opponent. Some Republicans, speaking in Trump’s defense, are arguing that potential corruption by the Bidens was a legitimate subject of investigation.

Biden has stressed repeatedly that independent news organizations have found that neither he nor his son did anything wrong. He argues that the accusations have been put forth by Trump and his allies simply because they “don’t want me to be the nominee.”

Still, during a recent town hall in Grinnell, Iowa, where Biden again touted his foreign policy experience, one questioner said he worried that the foreign dealings were a potential liability with voters.

“Every single solitary witness . . . has testified that Joe Biden didn’t do a single thing wrong,” Biden responded. “I did my job. I carried out the policy of the United States of America and, I might say very bluntly, very well.”

Some voters appear to be buying the argument. Jan Bingham, 64, of Cedar Rapids, said a big reason she supports Biden is his foreign policy experience and the impact it will have on her own life.

Her son is in the military. He spent the holidays with family but returns to active duty this week.

She and her son are worried about the future, she said. Before she attended Biden’s event in Vinton, the self-proclaimed news junkie received a text from her son: “Are we going to war with Iran?”

She said the prospect of war is her chief fear and will heavily influence her vote. “I don’t believe anything [Trump] says. You’ve given me no reason to believe your credibility,” Bingham said.

On the other hand, she said, “I do like Biden. He’s got the experience. He’s got the relationships with leaders in the world. It’s got to be somebody like him that’s not so extreme.”