HARTFORD, Conn. (AP) - Sen. Joe Biden rallied Connecticut Democrats Monday night, urging the party not to give Republican presidential candidate Sen. John McCain a free pass while Democrats Sens. Hillary Clinton and Barack Obama fight it out for the nomination.

No matter who wins the Democratic battle, Biden said voters need to know there is a stark difference between either candidate and McCain.

``John McCain is a clone of President Bush on every critical issue,'' he told about 1,100 Democrats who attended the state party's 60th annual fundraiser _ the Jefferson-Jackson-Bailey dinner.

Biden was glowingly introduced by Senate colleague Chris Dodd, Connecticut's senior senator. Both men, longtime friends, withdrew from the presidential race after poor results in the Iowa caucus in January.

While Clinton and Obama have tirelessly campaigned for Democratic delegates since then, McCain emerged early as the GOP front-runner and wrapped up the Republican nomination. Biden sought to tie McCain, whom he also called a friend, to President Bush and his policies, especially on the war in Iraq. He said McCain won't make the changes needed to withdraw troops.

``When it comes to Iraq, there is virtually no daylight between John McCain and George Bush. They are joined at the hip,'' he said.

Biden has not endorsed either of the Democrats but said both Clinton and Obama were ``great, potential nominees'' who've been able to rally strong support from voters. He urged rank-and-file Democrats not to get caught up in media predictions that the national convention will be a political disaster if the nominee is not yet determined.

``I am one of those who believe whoever the nominee is, the party will rally behind them,'' Biden said.

The Delaware senator dramatically stressed the importance of the November election, telling the party faithful that they've never cast votes in such a key race.

``So much is at stake. The national security, the physical security of our children, the retirement security of our parents,'' he said, adding that if ``we don't get it right'' in Iraq, the country could still be at war for another generation.

``It can be said, without fear of contradiction, this is the single most important election that any of you in this room have voted in,'' he said.

Biden, chairman of the Senate Foreign Relations Committee, received a standing ovation when he spoke of the thousands of deaths and injuries that the U.S. military has suffered since becoming involved in the Iraq War, which he said is costing $12 billion a month.

``Ladies and gentlemen, my fellow Democrats, this war must end,'' he said.

Organizers said the Monday's event was expected to raise about $300,000.

Dodd, who has endorsed Obama, took the opportunity to thank state Democrats for supporting him in presidential run. The party also honored longtime Manchester Democratic Town Committee Chairman Ted Cummings with its first William A. O'Neill Award, named after the former governor, who died last year.

Biden, 65, said he was due to have a ``small'' medical procedure at a Philadelphia hospital on Tuesday. He did not elaborate, but said he'd be out of work for a week. Nancy DiNardo, the state party chairwoman, said a former state representative, Vin Roberti, helped to raise money to pay for Biden's flight home so he could make it to the appointment.