State Sen. Mike Delph, R-Carmel, announced Wednesday he will not run for the U.S. Senate next year.
His decision leaves state Treasurer Richard Mourdock as the lone challenger to Sen. Richard Lugar, R-Ind., in the 2012 Republican primary election.
"My wife and daughters need me here in Indiana helping with homework, assisting with carpooling, and just being Dad," Delph said in a statement. "That is my number one obligation. My oldest turned 17 this month while my youngest turned five. I don't want to miss a moment of time with any of my daughters."
He also said, "Perhaps one day I will be better situated to bring my state legislative record of success to the national level."
Delph said more than a month ago that he would make a decision shortly after Labor Day about whether he would run for the U.S. Senate. He said Wednesday that he had been encouraged by others to be a candidate for the last nine months.
Mourdock said in a statement: "Senator Mike Delph is a solid Conservative and true family man. I have known Mike for over 10 years, and he will continue to do a great job in the Indiana State House."
Delph and Mourdock were rivals in 2002 for the GOP nomination for secretary of state won by Todd Rokita at the party's state convention. Rokita won the fall general election, served two terms and was elected to Congress last year in the 4th District.
Hoosiers for Conservative Senate, a coalition of state tea party groups hoping to unseat Lugar, will have a convention Sept. 24 in Greenfield to endorse a candidate -- sure to be Mourdock now -- in the Republican primary.
"We're so grateful for Senator Delph and what he brings to our State. He is a man of integrity and a man of wisdom and a genuine conservative," said Monica Boyer, a Warsaw resident and co-chairwoman of Hoosiers for Conservative Senate.
Tea party activists say Lugar, who was first elected in 1976 and has not seen a GOP primary challenge since then, has not been conservative in his votes on immigration, gun rights, Supreme Court nominations and arms reduction.
Delph wrote the state's new immigration law, which has been blocked by a lawsuit contending it gives police broad powers to arrest immigrants.
"I will continue fighting for traditional conservative values and supporting solid conservatives for public service opportunities across all levels of government," Delph said in his statement.
Lugar's campaign did not respond immediately to a request for a comment about Delph's decision. The campaign for Rep. Joe Donnelly, D-2nd, who seeks the Democratic nomination for Senate, declined to comment.