WASHINGTON — On Oct. 10, 2002, Sen. Lincoln D. Chafee cast the only Republican vote against a measure to let President Bush use military force in Iraq.

Democratic Senate candidate Sheldon Whitehouse first spoke out against the Iraq war last year after he began his campaign for Chafee’s seat. Whitehouse has said he would have voted as Chafee did — against the war measure that passed the Senate with a large bipartisan majority four years ago.

Behind this appearance of agreement on the leading issue of this election year, Chafee and Whitehouse differ sharply on key aspects of the war. They attack each other even more sharply.

Whitehouse accuses Chafee of being “extremely quiet” on the war and of seeming to be “satisfied” to have Donald H. Rumsfeld as secretary of defense.

Chafee says Whitehouse’s long silence on the war suggests that — like such Democrats as Sen. Hillary Rodham Clinton of New York — Whitehouse might have been an early supporter. He accuses Whitehouse of “flip-flopping” in his on-and-off embrace of hard deadlines for bringing U.S. troops home from Iraq.

In an interview last week, Whitehouse said he did not speak out against the war in 2002 because “it was not an issue” in his race for governor that year. He said he spoke out “when people took an interest in what I had to say” after he became a Senate candidate in the spring of 2005. Whitehouse said he has since held a consistent, three-point position: the president should “announce that we are going to get the troops out”; the military should execute the withdrawal; and the United States should step up diplomacy during the withdrawal to solve the problems in Iraq.

A look at the record shows that Whitehouse did call in 2005 for a “rapid and responsible” withdrawal from Iraq. But he has also supported — and later backed away from — detailed prescriptions about when and how the United States should get out of Iraq.

Last fall, Whitehouse rejected calls made by his opponents in the Democrat primary to pull U.S. troops out of Iraq according to fixed deadlines.

By last spring, however, Whitehouse had called for the same strict pullout schedule as one of his rivals: bring home the troops by the end of this calendar year.

In June, Whitehouse went further, endorsing legislation that would have forced the withdrawal of U.S. troops from Iraq by July 1, 2007, and would have imposed a series of specific directives on the military.

Chafee opposed that measure, offered by Sen. John F. Kerry, D-Mass.

“I’m not ready to have the legislative body dictate to the executive branch” on questions of troop deployment, Chafee said at the time. Kerry’s amendment failed, 86 to 13, with Rhode Island Sen. Jack Reed and a large majority of fellow Democrats opposed.

Last week, Whitehouse suggested that he had not meant to endorse all the specifics of Kerry’s legislation. He said he supported the Kerry measure as “an expression of congressional dissent with the president’s policy.” Whitehouse said he does not want the Congress or the president to fix a specific “out day” for the troops in Iraq.

Asked why he had endorsed the Kerry amendment’s hard deadline of mid-2007 for U.S. military withdrawal from Iraq, Whitehouse answered: “The United States Senate was not conferring with me when they drafted these resolutions.”

When Whitehouse backed away from any deadline for troop withdrawals last summer, he laid the responsibility at Mr. Bush’s door, saying that because the president had not acted on Whitehouse’s call for a public pullout plan, the “march of time” had now made it impractical.

Chafee offered a more critical explanation: Whitehouse “flip-flopped” because he saw that he had gotten “too far out in front of Jack Reed” by backing the kind of fixed timetables for withdrawal that Reed and other leading Democrats have opposed.

Whitehouse said Chafee’s criticism is incorrect.

Whitehouse also reiterated his critiques of Chafee. Since he refuses to demand Rumsfeld’s resignation, the Republican senator “appears satisfied to leave Rumsfeld in place,” Whitehouse said. Whitehouse has also claimed Chafee has been “quiet” on the war and lacks a “plan or idea on how to proceed.” Also, Whitehouse accuses Chafee of wanting the United States to consult with Iran and Syria before making troop deployment decisions.

To the charge of being “quiet” on the war, Chafee offers his vote against the war — one joined in by only a minority of Senate Democrats.

Pointing to Democrats who have campaigned against him in Rhode Island, Chafee said, “Mr. Whitehouse is having politician after politician come in on his behalf who voted for the war.” Senator Clinton and others, Chafee said, “should be standing up and saying ‘I was wrong on the war. Senator Chafee was right.” After long opposing efforts to force an end to U.S. involvement — warning that a swift U.S. pullout might lead to “chaos” — Chafee has softened his stance. Chafee said he may favor some form of withdrawal schedule if the United States does not soon begin diplomacy with the nations bordering Iraq, including Iran and Syria.

Chafee was asked how he squares that position with his consistent opposition to withdrawals. He said that such a shift might help to send “a message to the executive that the present plan is not working.” Echoing John Warner of Virginia, chairman of the Senate Armed Services Committee, Chafee said he expects to reassess the situation in Iraq early next year.

Chafee also said it was “ridiculous” for Whitehouse to suggest he seeks foreign approval of U.S. military plans. Chafee spokesman Stephen Hourahan added that Chafee’s call for diplomacy means that he wants the United States to discuss the conflict in Iraq with Iraq’s neighbors.

Chafee said “symbolic” calls for Rumsfeld’s resignation are “irrelevant to the grand scheme of how we’re going to fix” the “complex and challenging” problems in Iraq.

As for his plan for Iraq, Chafee pointed to his support of initiatives by Reed and other Democrats who oppose fixed pullout schedules. Chafee cast the only GOP vote last summer for a non-binding resolution, offered by Reed and others, that would have asked Mr. Bush to set plans for “redeployment” of U.S. troops out of Iraq.

The measure, which failed, would have left it to the president and military brass how to proceed after such an announcement.

Whitehouse has said he would have voted for that measure as well as Kerry’s hard deadline.