INDIANAPOLIS — Indiana congressman and superdelegate Andre Carson has endorsed Sen. Barack Obama, becoming the first of the state’s five U.S. House Democrats to announce support for a presidential candidate.

Superdelegates could determine who gets the nomination in the tight race between Obama and New York Sen. Hillary Rodham Clinton.

Carson said Tuesday that Obama will fight for hardworking Americans.

“He is a man who represents a new generation of leadership that will take responsibility for changing our country,” Carson said.

Carson was elected in a March special election to finish the term of his late grandmother, Julia Carson. He said the endorsement was a difficult decision to make because he and his family have love and respect for the Clintons.

“This is a decision that I felt in my heart was the right thing to do,” he said.

Carson faces three serious challengers in the state’s May 6 primary, and said Obama is endorsing him in the race.

Obama’s campaign issued a statement Tuesday to thank Carson for his support.

“I look forward to working with him to help strengthen our economy, bring the war in Iraq to an end and ensure all Hoosiers and Americans have access to affordable health care they deserve,” Obama said.

Jonathan Swain, a spokesman for Clinton’s Indiana campaign, said he respects Carson’s decision but that the campaign remains focused on Clinton’s message to the voters of Indiana.

“We think she is the strongest candidate to deliver solutions to the challenges Hoosiers are facing,” Swain said.

Indiana has 13 superdelegates — party insiders and elected officials who are free to vote as they wish at the Democratic convention — plus 72 pledged delegates determined by the primary. Neither Obama nor Clinton will be able to clinch the 2,025 delegates needed to win the nomination without support from the party’s nearly 800 superdelegates.