Indiana Republican US Sen. Candidates Debate Before Primary

(With additional reporting from The Associated Press)

The two candidates vying for the Republican nomination in Indiana's U.S. Senate race debated Wednesday night in Indianapolis.

Richard Lugar has represented Indiana in the U.S. Senate for more than three decades, but State Treasurer Richard Mourdock hopes to change that by defeating him in the May 8 primary.

Lugar is respected for his foreign policy expertise, but Mourdock didn't shy away from taking stances on international issues on everything from defending Israel to the U.S.'s relationship with Russia.

"I think they are more foe than friend," Mourdock said. "Looking ahead, I think we are going to see more troubling times with Russia. We have to be a strong nation. We cannot withdrawal from the world. We've got to stop leading from behind."

Lugar said Russia is neither a friend or foe, but a country that the U.S. needs to deal with. Mourdock occasionally struggled answering intricate policy questions, meanwhile, that played more to Lugar's strengths.

In one case Mourdock seemed to errantly state that a federal ethanol mandate that started in 2005, began in 2011.

Both candidates think reducing the size of government and repealing the federal health care law are good ideas.

Mourdock touted his conservative credentials, but Lugar said his conservative roots go deep too, from his service in the Navy to managing a family farm.

"These are the conservative elements of my life and they are expressed in my votes," Mourdock said. "The work we have been doing both in the economy as well as in foreign policy to bring security for America."

In one of the clearest distinctions between the two men, Mourdock called for an end to corn ethanol subsidies, something Lugar has routinely backed citing Indiana's heavy reliance on agriculture.

The two even disagreed on what exactly ethanol subsidies do to the price of gas, with Lugar saying ethanol was helping to keep prices down and Mourdock saying they were making prices higher. Lugar praised ethanol saying it lowers the price of gasoline and helps Indiana farmers.

"It's a Hoosier product with Hoosiers producing it on farms here that have meant higher values for corn and certainly higher land values in this state."

On domestic issues, the two men often agreed with each other. Lugar at times sought to ally himself with Wisconsin Rep. Paul Ryan, touting Ryan's budget plan, which has become a rallying point for many conservatives.

One exchange fairly defined the tenor of the entire race: When given the chance to shore up his weakest spot, by defining how he is a conservative, Lugar opted for a roundabout answer dealing with his family history and serving in the military.

"These are conservative elements of my life and they're expressed in my votes and the work we have been doing both in the economy as well as in the foreign policy to bring security for America," he said. "We understand conservative values."

The debate was a stark difference from a nasty Republican primary battle that has been dominated thus far by questions over Lugar's residency and his support for President Barack Obama's Supreme Court nominees.

Lugar is facing one of his toughest election battles as he seeks a seventh term. A series of polls has shown the tea-party backed Mourdock closing in on Lugar in recent months and conservative groups have upped their attacks in the last two weeks on the longtime senator.

As of last week, a trio of outside groups supporting Lugar had bought $370,000 worth of airtime across the state, while the Club For Growth alone had bought roughly $735,000 to oppose to Lugar.

Super PACs have sprouted up as a potential force in the Senate race, with two forming to back Lugar, and Lugar opponents splitting their spending between the parent group and the PAC.

By far the biggest spender in the air wars, however, has been Lugar himself, who has bought roughly $1.9 million of airtime. Mourdock has paid for $360,000 of airtime, according to spending totals maintained by Indiana Democrats.

Meanwhile, Congressman Joe Donnelly of South Bend, Indiana is running unopposed in the Democratic Primary for the Senate seat.

(AP Photo/Darron Cummings, Pool)