Arlington Heights, Ill. ? Alan Keyes, a two-time presidential candidate who lives in Maryland, announced Sunday that he had accepted the Illinois Republican Party’s nomination and would run for the U.S. Senate.

With less than three months before the election, Keyes acknowledged it would be difficult to beat Barack Obama, the state senator whose speech at the Democratic National Convention in Boston launched him into the national spotlight. This is the first U.S. Senate race in history where both candidates from the two major parties are black, assuring that the Senate will seat its fifth black member ever.

“We do face an uphill battle, there’s no doubt,” said Keyes, 54, who promotes a Christian philosophy. He accepted the nomination Sunday at a rally in this Chicago suburb.

The battle to fill the seat held by retiring Republican Sen. Peter Fitzgerald would be difficult, said Keyes, who has never won a federal election. If he wins, “the victory is for God,” he said.

Critics in the state Democratic Party dismiss Keyes as an opportunist and describe the GOP selection as “sad.”

“Twelve and a half million people in our state, and the Illinois Republican Party was unable to come up with one person to run for the United States Senate,” said Sen. Richard Durbin (D-Ill.). “Their selection process made it very clear that when it comes to the future of the Republican Party, moderates need not apply.”

Keyes has served as a State Department and U.N. official, and he is a former radio and cable-TV host. He previously criticized politicians such as Hillary Rodham Clinton for running for office outside their home state.

But Illinois Republicans say Keyes’ race, education and conservative views are a compelling combination. Keyes opposes abortion and gay marriage, affirmative action and gun control. He has called for eradicating the income tax and instituting a national sales tax instead.

Republicans say this puts him in stark contrast to Obama, who supports affirmative action and abortion rights, and has voted in favor of background checks on all gun sales. He’s pro-labor and has proposed offering tax incentives for companies that keep high-paying jobs in the United States.

“(Obama) has never seen a spending bill he couldn’t find some excuse for and has never seen a tax increase he didn’t like,” Keyes said.

Obama, upon hearing the criticisms, called on his rival to run a positive race. In a statement issued Sunday, Obama said, “As Mr. Keyes begins to travel the state, he will see that families here are concerned about quality jobs, making health care more affordable and ensuring our children get the best education possible. And Illinoisans want a Senate candidate who will attack the problems they and their families face rather than spending time attacking each other.”