WASHINGTON — Sen. John Kerry, President Barack Obama's nominee for secretary of state, collected pledges of support Thursday and testified at his confirmation hearing that U.S. foreign policy should be defined by a helping hand as well as military strength.

The Massachusetts Democrat discussed Iran, Syria, climate change and a variety of issues with members of the Foreign Relations Committee at a hearing that recalled an unusual American life — son of a diplomat, Navy lieutenant who volunteered for Vietnam, anti-war protester, five-term senator, unsuccessful nominee for president, and Obama's unofficial envoy.

The nearly four-hour hearing also provided an odd juxtaposition as Kerry, a member of the panel for 28 years and its chairman for the past four, sat alone in the witness chair. At one point, Sen. Bob Menendez, D-N.J., the incoming chairman who presided, mistakenly referred to Kerry as "Mr. Secretary."

The current secretary, Hillary Rodham Clinton, introduced Kerry, calling him "the right choice." She is stepping down after four years.

The committee is expected to approve Kerry's nomination. A full Senate vote will take place Tuesday, Senate Majority Leader Harry Reid said.

"American foreign policy is not defined by drones and deployments alone," Kerry said in outlining his views. "We cannot allow the extraordinary good we do to save and change lives to be eclipsed entirely by the role we have had to play since Sept. 11, a role that was thrust upon us."

Kerry spoke out strongly for dealing with climate change, providing food and energy security and humanitarian assistance. He also spoke of robust foreign aid, but he insisted that the country must get its fiscal house in order to lead in the world.

"More than ever, foreign policy is economic policy," said Kerry, who described himself as a "recovering member of the supercommittee." That bipartisan panel failed in 2011 in its mandate to come up with a deficit-cutting plan.

Faced with Iran's nuclear program, Kerry said the United States will do what it must to prevent Tehran from obtaining a nuclear weapon, but he also signaled that diplomacy remains a viable option.

"I repeat here today: Our policy is not containment. It is prevention, and the clock is ticking on our efforts to secure responsible compliance," Kerry said.

The senator said he was hopeful that the U.S. and other nations could make progress on the diplomatic front, but that Tehran needs to relent and agree to intrusive inspections.

"If their program is peaceful, they can prove it," he said.

In an unexpected exchange, Kerry found himself defending Obama's pick of Republican Chuck Hagel to be the next defense secretary against GOP criticism.

Sen. Bob Corker, the senior Republican on the panel, expressed concerns about Hagel's support for an 80 percent reduction of U.S. nuclear weapons, a major issue for the Tennessee lawmaker and his home state. The Y-12 nuclear facility is located near Oak Ridge, Tenn., and any cuts or delays in modernization to the nuclear arsenal would have an impact on local jobs.

"I know Chuck Hagel. And I think he is a strong, patriotic former senator, and he will be a strong secretary of defense," Kerry said.