WASHINGTON » The calls come at all hours from time zones across the country as anxious House Democrats reach out to Rep. Nancy Pelosi, asking her to make her case for a strike in Syria.

"What I have said, including to some of my closest friends in Congress who are mostly in doubt: I want you to know that I don’t like the use of force," said Pelosi, the California Democrat and House Democratic leader. "But I think it should happen" in Syria.

Pelosi, who led Democratic opposition to the Iraq War resolution sought by President George W. Bush, is now charged with rounding up enough votes in a chamber where her party is in the minority to win approval of a use-of-force measure requested by President Barack Obama. The effort comes as members of her leadership team and Senate Democrats are privately seething over the position their party’s president has put them in: rounding up votes for a measure that most of the country does not support.

House Republicans, whose leaders support the effort but who themselves largely do not, have made it clear that the burden rests with Pelosi, a notion she rejects. "If we’re going to have a product, it’s going to have to be strongly bipartisan," she said.

While Speaker John A. Boehner has shown little ability to sway the most conservative members of his party disinclined to help Obama, Pelosi has maintained credibility across a broad swath of her caucus. It is a credibility hard-earned through years of legislative victories that have left many of her own members battle-scarred, including on health care, the bailouts of the auto industry and the financial sector, and climate change legislation. That loyalty faces a test as she tries to build a consensus, without the power of the gavel.

Unlike Boehner, Pelosi has written daily letters to colleagues encouraging them to come to an agreement on a measure, taken dozens of calls from lawmakers, and arranged briefings for scores of House Democrats with high-level administration officials, including briefings specifically for Hispanic, black and freshman members.

Pelosi said that while she was sympathetic to her members’ reluctance, the stakes with chemical weapons were simply too high. "I believe stopping weapons of mass destruction is a pillar of our national security," she said.

"We have to make sure tyrants do not think they can do that with impunity," she added. "I think war should be obsolete. I don’t think it is a reasonable way to resolve conflict. I think we should eliminate it as a possibility. But we haven’t yet."

While Pelosi is doing Obama’s bidding, the task at hand synthesizes years of Pelosi’s deep personal interests in human rights issues and national security, her complicated history with liberals on matters of war, and her legislative prowess, which hinges on a near obsession with counting and securing votes.

Pelosi, who has spent decades pressing human rights issues in China, Kosovo, Darfur and beyond, spoke out in favor of action against the Syrian government before Obama made his case, saying, "Assad gassing his own people is an issue of our national security, regional stability and global security."

As a senior member of the House Intelligence Committee, she was an early opponent of the Iraq War and voted against its authorization. She later faced anti-war protesters outside her San Francisco home after vehemently defending bills that paid for that war.

"On national security issues there is no one-size-fits-all with Nancy Pelosi," said Rep. Steve Israel, D-N.Y. "She has been very muscular on protecting human rights abroad. She is hawkish on some issues, dovish on others. She has a very complex view on foreign policy, and by explaining them to members, she can bring them along."

In her early years in the House in the 1980s, she pressed the Chinese government on human rights, and she lobbied for years on behalf of Liu Xiaobo, who spent a decade in prison for his critical articles on the government there. As speaker, she was the highest-ranking U.S. official to attend Liu’s Nobel Peace Prize ceremony, an honor she called "a culmination of years of work" and one of her "proudest moments."

More recently, she has been involved in the case of Chen Guangcheng, who escaped house arrest in China. She has traveled extensively through the Middle East and Afghanistan, China and Africa, including Darfur, where she said she was deeply moved by the plight of refugees.

"The issue of human rights is something that has been a very big priority for me," she said. "Wherever violations have taken place, it does not mean I advocate military action in response. It just meant we would shine a bright light. It has always been a driving force for me, in part from my Catholic faith."

Her views on military conflict have largely formed over the 20 years she has served on the Intelligence Committee, where she voiced opposition to the Iraq War. "As the senior Democrat on Intel, I said, ‘I am telling you the intelligence does not support the threat,’" she said. "An overwhelming number of Democrats voted against the war. They took my word for it."

Those lapses in intelligence helped contribute to a skepticism and war-weariness among the public and in Congress, which now bedevils Obama in his far more limited goal of a strike against Syria. "Now who pays the price?" she asked.

Public opinion may be against action, but Pelosi said that should not be used as an easy escape route. "We have to have the courage on the basis of what we know, on the basis of our values," she said.

In some ways, the dynamic of the Syria measure has components similar to the 2008 bank bailout bill, known as the Troubled Asset Relief Program, or TARP. That measure, designed to shore up the financial sector during the housing crisis, was requested by Bush, and it met skepticism on both sides of the aisle. The legislation failed spectacularly on its first vote.

Pelosi, then leading the Democratic majority, provided the crucial votes that Boehner, then the Republican leader, failed to garner among uneasy Republicans.

"The interesting thing with TARP," said John Lawrence, who served as Pelosi’s chief of staff for eight years, "was there you had a Republican president with a Democratic speaker who was highly critical of the lax regulatory conduct by the Bush administration.

"Still, despite that, she still went to bat to make the policy happen because it was best for the country. She had no interest in making the Bush administration look good a few weeks before the presidential election. But she had to help the country in a crisis."

Pelosi has repeatedly insisted that members will not be pressured on the Syria vote, saying that she will listen to her conference, try to incorporate members’ ideas into legislation and then let them vote their conscience.

Whether that approach will bring Obama the votes he needs is very much in question. "She has a good chance to be influential," said Rep. Michael E. Capuano, D-Mass. "But war and peace does not subject itself to arm twisting. I can’t imagine she will try."