Dec. 17 (Bloomberg) -- Republican presidential candidate John McCain was endorsed today by Senator Joseph Lieberman, who was the Democratic nominee for vice president in 2000.

``I know it's unusual for a Democrat to be endorsing a Republican,'' Lieberman said at an event in New Hampshire today. ``Political parties are important in our country, but they're not more important than what's best for our country.''

Lieberman said he was endorsing McCain because he believes McCain is the best qualified to confront threats to U.S. interests around the world, including terrorism.

Lieberman made a specific bid for New Hampshire's independent voters, who can vote in that state's Jan. 8 primary, to support McCain. His endorsement is unlikely to push Democratic-leaning independents or Democrats to support McCain; it could gain some votes for McCain among moderate Republicans or Republican-leaning independents, one analyst said.

``This will give those voters one more reason to support McCain,'' said Dante Scala, a professor of political science at the University of New Hampshire. Lieberman ``doesn't carry much weight with Democrats'' because of his strong support for the war in Iraq, he said.

Lieberman won re-election as an independent after losing the Democratic primary in Connecticut in 2006. He describes himself as an ``independent Democrat'' and still caucuses with Democrats in the Senate, giving them a one-vote majority in that body.

``We desperately need our next president to break through the reflexive partisanship that is poisoning our politics today,'' Lieberman said. ``I honestly believe that he can reunite our country.''

McCain, who was also endorsed by the Des Moines Register and Boston Globe this weekend, said he had worked across party lines with Lieberman in the Senate to strengthen national security.

To contact the reporter on this story: Mark Drajem in Washington at mdrajem@bloomberg.net

Last Updated: December 17, 2007 10:42 EST