Sen. James Jeffords announced Thursday his decision to leave the Republican Party and become an independent, a move that will give Democrats control of the Senate for the first time since 1994. 

"In order to best represent my state of Vermont, my own conscience and principles that I have stood for my whole life, I will leave the Republican Party and become an independent," Jeffords said as his supporters erupted in cheers.

Jeffords made it clear that his decision was a response to recent GOP electoral success.  His shift was a repudiation of the conservative policies pursued by the White House and the GOP majority on Capitol Hill. 

"Increasingly, I find myself in disagreement with my party. I understand that many people are more conservative than I am and they form the Republican Party. Given the changing nature of the national party it has become a struggle for the leaders to deal with me and indeed for me to deal with them," Jeffords said.

Jeffords said that he had been "struggling with a very difficult decision" for the past several weeks but said he made his decision Wednesday night after meeting with moderate colleagues in the Senate.

"I met with my moderates yesterday. It was the most emotional time I have ever had in my life, with my closest friends urging me not to do what I was about to do because it affected their lives substantially."

State Republican leaders were furious about Jeffords' decision. "My concern for Jeffords is that his legacy will be as one of Benedict Arnold," said Skip Vallee, the state GOP's national committeeman.

But interviews Wednesday in Jeffords' hometown of Rutland found most people supportive of the senator.

"I think the rest of the country is getting a little bit better picture of what it is to be a Vermonter," said John Alexander. "He's voting his conscience. I just wish the rest of the Congress was like that."

Jeffords said his move will take effect after the signing of the tax bill that made it through the Senate yesterday, and that he promised the president he wouldn't interfere with that legislation. 
  
Jeffords has told Senate leaders he will caucus with Democrats and vote with Democrats in terms of organizing the Senate. Sen. Tom Daschle, D-S.D., will become majority leader, with the ability to bring bills to the floor. Democrats will take over as chairmen of most committees.

In an attempt to keep Jeffords in the party, Sen. Republican Leader Trent Lott of Mississippi offered Jeffords an appointed leadership position, more money for favored education programs and a waiver of term limits to let him remain chairman of the Education Committee beyond the end of next year. 

At the same time, Senate aides said Jeffords had approved staff meetings with Democrats to discuss preparations for taking over the chairmanship of the Environment and Public Works Committee, the post Democrats were offering if he would bolt the GOP.

Anatomy of a Defection

Jeffords,  67, was a lifelong Republican who has often been at odds with conservatives in his party and has been among the most liberal members of the Senate. Given the senator's willingness to go against his own party, rumors of his leaving the GOP have routinely popped up over the years.

According to the Almanac of American Politics, "Before 1992 [Jeffords] voted against the Reagan budget and tax cuts, against Clarence Thomas, against the B-2 [bomber] and SDI. He opposed the Clinton budget and tax package in 1993, but voted for family and medical leave, motor voter, national service, the Brady bill and the 1994 crime package, despite anti-gun control feeling in Vermont."

Jeffords angered the White House this spring when he refused to support Bush's budget with its $1.6 trillion, 10-year tax cut. Instead, he sided with a bipartisan group of lawmakers who forced changes on the Senate floor. The result was the first high-profile defeat for the new administration. 

Shortly after that, Jeffords was not invited to the White House for a National Teacher of the Year award ceremony honoring a Vermont high school educator, a move widely viewed as political payback. 

In addition, some GOP aides have whispered that the White House might retaliate by seeking changes in a dairy support system that benefits farmers in Vermont and the Northeast. 

Bush did not contact Jeffords personally during the budget debate, leaving it to Cheney and administration staff officials to try to swing a deal for the senator's support. 

But Jeffords met with President Bush and Vice President Cheney Tuesday, perhaps in an effort to convince him to stay in the party. One Senate Republican told Fox News that Jeffords described his meeting with Bush as "uncomfortable and unproductive." A Democratic senator confirmed that Jeffords had shared with him that the conversation was "not good."

-- Fox News' Julie Asher, Sharon Kehnemui, Carl Cameron, and The Associated Press contributed to this report