HILLSBOROUGH, N.H. (AP) — The Democratic vice presidential nominee in 2000 endorsed Republican John McCain for president on Monday, scandalizing Democrats in Washington and giving the GOP hopeful a much-needed boost in New Hampshire where independents outnumber Republicans and Democrats.

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.