A Philosophy of Diplomacy First, Force Last

As the Bush administration was fine-tuning its plan to invade Iraq, Senator Joseph R. Biden Jr. helped draft a proposed resolution that emphasized the need for diplomatic efforts to dismantle Saddam Hussein's weapons programs but gave President Bush the authority to use military force as a last resort.

The measure, Mr. Biden wrote in his memoir, was intended to strengthen Secretary of State Colin L. Powell's hand in getting United Nations weapons inspectors into Iraq. But it was blocked, and Mr. Biden invoked the same rationale in voting for the tougher measure authorizing military action that was passed by the Senate in October 2002.

In three decades in Washington, Mr. Biden has been one of the Democratic Party's most energetic leaders on foreign policy. He has held countless hearings, opined volubly on security issues and, by his own account, advised Mr. Bush on matters like calling for the further expansion of NATO.

But should he be elected vice president on the Democratic ticket with Senator Barack Obama, Mr. Biden would have a role that has eluded him: a seat in the inner sanctum of White House decision-making. He would be advising a president who would take office with slim credentials in foreign affairs — and who, as a candidate, has said he wants a vice president who will offer blunt and dissenting opinions.

Mr. Obama opposed the war in Iraq from the beginning, staking out a position against it while still a state legislator in Illinois, around the time Mr. Biden was voting to authorize military force. Even before his unsuccessful campaign for the Democratic presidential nomination, Mr. Biden took a different approach to Iraq from Mr. Obama's; Mr. Biden called for governing power in Iraq to be decentralized among three largely autonomous Sunni, Shiite and Kurdish regions.

But like Mr. Obama, Mr. Biden has for several years opposed the administration's handling of the war, especially Mr. Bush's decision to send additional troops — an administration strategy that military experts say has helped to reduce violence in Iraq. Both of them now support substantially withdrawing combat brigades from Iraq and building them up in Afghanistan.

More generally, both of them fit into the mainstream of Democratic thinking on foreign policy and national security, which emphasizes working with allies and using force as a final recourse.