Sen. Joseph Lieberman, an independent who caucuses with the Democrats, said he chose his longtime Senate colleague because he has the best shot of breaking partisan gridlock in Washington. Both men also are strong and vocal supporters of the war in Iraq.
"On all the issues, you're never going to do anything about them unless you have a leader who can break through the partisan gridlock," said Lieberman, who was Al Gore's running mate seven years ago. "The status quo in Washington is not working."
Independents hold considerable sway in New Hampshire's first-in-the-nation primary on Jan. 8, and they helped McCain win the state's Republican primary in 2000 over George W. Bush. As of March of this year, voters who are independent - undeclared is the official term - accounted for 44 percent, compared with 30 percent Republican and 26 percent Democrat.
Traveling with Lieberman Monday morning to Hillsborough's American Legion hall, McCain said the Connecticut senator is his answer to the people he hears in every town hall meeting who ask, "Why can't you all work together?"
Lieberman said McCain's approach to Iraq and his credentials on national security are the main reasons he is supporting a Republican for president.
But both men said the election seems increasingly about the economy and domestic issues rather than Iraq. On those issues, Lieberman acknowledged he does not always see eye-to-eye with his 2008 pick. But, said Lieberman, McCain is always straightforward about where he stands.
Leading Democrats weren't happy with his latest move.
Senate Majority Leader Harry Reid of Nevada said in a statement: "I have the greatest respect for Joe, but I simply have to disagree with his decision to endorse Senator McCain."
Al From, the founder and CEO of the centrist Democratic Leadership Council, said, "I am very saddened by Senator Lieberman's choice and profoundly disagree with it. We need to elect a Democratic president in 2008."
For McCain, behind in the polls here but gaining, the endorsement carries the risk of alienating conservatives who have been critical of his support for immigration and campaign finance reforms.
"If I get some criticism for aligning myself with a good friend I have worked with for many years, I will be more than happy to accept that criticism," McCain said.
For Lieberman, it marks another turn away from the Democrats.
"Political party is important, but it's not more important than what's good for the country and it's not more important than friendship," Lieberman said.
Lieberman won re-election to the Senate in 2006 as an independent, after losing the Democratic primary to upstart Ned Lamont largely because of his support for the war. High-profile Democrats abandoned him after the primary defeat, including his Connecticut colleague, Sen..
Although Dodd also is seeking the presidency, Lieberman backed McCain. He said he had intended to wait until after the primaries to make a choice for the 2008 presidential race, but McCain asked for his support and no Democrat did.
Word of the endorsement follows several other high-profile announcements for McCain, includingand The Boston Globe.
McCain has largely ceded the Iowa caucuses to front-runnersand , but the Register said, "McCain is most ready to lead America in a complex and dangerous world and to rebuild trust at home and abroad by inspiring confidence in his leadership."
The Globe, while not based in New Hampshire, circulates in New Hampshire's vote-rich southern tier. McCain has focused his campaign on the Granite State, hoping to repeat his 2000 victory over George W. Bush.
"The iconoclastic senator from Arizona has earned his reputation for straight talk by actually leveling with voters, even at significant political expense," the Globe wrote.
McCain has also picked up endorsements from The New Hampshire Union Leader, the state's largest newspaper, and The Portsmouth Herald.
"U.S. Sen. John McCain will tell you the truth, even if it costs him the election," the Herald wrote.
McCain, campaigning Sunday in Florida, said he expected the endorsements would help him with undecided voters, especially registered Republicans.
"All of them say the same thing - that I have the experience and the judgment to lead this country and that I have been the one who is presidential," the senator said. "Obviously that will help me as we get down in the last few weeks before the Iowa caucuses, New Hampshire primary, Michigan and South Carolina primaries and the Florida primary."