WASHINGTON — After months of personal soul-searching and political pressure, Rep. John Lewis on Wednesday formally announced that he's switching his influential support from Sen. Hillary Clinton to Sen. Barack Obama, whom Lewis now sees as the heir apparent to the racial progress Lewis himself has spent his life fighting for.

Lewis cited the overwhelming preference for Obama in his Atlanta district as a reason for his change of heart. But he also talked about Obama's campaign as a transformational moment, an opportunity born of Lewis' own sacrifices in the 1960s civil rights movement.

"Something's happening in America, something some of us did not see coming," Lewis said. "Barack Obama has tapped into something that is extraordinary.

"It's a movement. It's a spiritual event," Lewis said of the surging Obama campaign. "It's amazing what's happening."

Lewis had not talked with Obama or Clinton prior to announcing his switch, so it's unclear what role he'll play as the election continues.

"I have not been asked to campaign for Sen. Obama," Lewis said in a statement released later Wednesday. "I support his candidacy for president and will cast my vote for Sen. Obama as a superdelegate at the Democratic convention."

Obama issued a statement Wednesday afternoon, saying, "John Lewis is an American hero and a giant of the civil rights movement, and I am deeply honored to have his support."

Clinton, questioned about Lewis during a satellite interview with Houston television station KTRK, said: "I understand he's been under tremendous pressure. He's been my friend. He will always be my friend. At the end of the day, it's not about who is supporting us, it's about what we're representing, what our positions are, what our experiences and qualifications are, and I think that voters are going to decide."

Lewis' announcement last October that he was backing Clinton, a longtime friend, over Obama, the nation's first truly viable African-American candidate for the presidency, angered many of Georgia's black constituents and numerous civil rights elders who had fought for black voting rights alongside Lewis.

It also created political opposition for Lewis, who has run for Congress unopposed for the past decade. The Rev. Markel Hutchins of Atlanta recently announced his plans to oppose Lewis in this year's Democratic primary because, Hutchins said, Lewis has lost touch with his constituency.

"It was a long, hard, difficult struggle to come to where I am," Lewis said.

At the time he endorsed Clinton, Lewis said, Obama was an unknown and Clinton not only had across-the-board appeal but also was clearly ready to lead the nation.

"I did it because I felt in my heart that I had to support Mrs. Clinton because of our friendship," Lewis said.

"I don't regret it," Lewis added. "The political thing to do would have been to have done nothing, to not endorse anyone.

"Sometimes, you have to be on the right side of history," he said.

Lewis' comments were intended to clear up confusion caused about a week ago when The New York Times reported that he was going to vote for Obama over Clinton as a superdelegate to the Democratic National Convention this summer if neither had enough delegates to declare victory outright. Lewis' office called the report inaccurate but never clarified whom he was supporting.

In an interview Wednesday, Lewis said his decision was an anguishing one.

During his last visit to Selma, Ala., where in 1965 police beat him nearly to death during a protest, Lewis stood between Clinton and Obama and praised the potentially historic election of both.

Former President Bill Clinton attended Lewis' 60th birthday party, but Obama was at his 65th.

With Lewis' switch to Obama -- along with Rep. David Scott, another Atlanta Democrat, who also left Clinton for Obama -- all of Georgia's African-American congressmen are now backing Obama.

Georgia's other congressional Democrats -- Rep. Jim Marshall of Macon and Rep. John Barrow of Savannah -- still have not endorsed either of their party's presidential aspirants.

Wednesday was the 48th anniversary of the day Lewis was arrested for the first time -- at a Woolworth's lunch counter in Nashville that did not serve blacks. And he's now talking about Obama as the heir of the civil rights fight.

"Mr. Obama is the embodiment of the hopes, dreams and aspirations of a lot of people," Lewis said. "He represents something different, something new. But he also represents a long line of individuals who come around from time to time who carry the aspirations of the people."

-- The Associated Press contributed to this story.