After struggling at times during the early Republican primary campaign, U.S. Sen. Richard Lugar sounded more like the legislator he's been for the past 35 years in a debate Wednesday night with Indiana Treasurer Richard Mourdock.

But while the confident Lugar often had a better grasp on the questions he was answering, Mourdock showed more poise than the veteran lawmaker. The contrast highlighted what has been an underlying argument from Lugar's opponents throughout the campaign: He needs to retire.

In all, the two were genial toward each other throughout the hourlong debate, lacking much of the vitriol that has dominated the campaign advertising so far. Mourdock, at one point, blankly agreed with a vague answer from Lugar that government should not be involved in contraceptive questions, saying "I think I'll do a ditto."

The candidates' only debate came as both ramp up their attacks in the race, which has shaped up to be one of the toughest election battles ever for the 80-year-old senator once considered so invincible that Democrats in 2006 chose not to field a challenger.

A strong anti-incumbent mood and pressure from the right to define who really is a conservative have forced Lugar into a frantic defense as he seeks a seventh term, and a series of polls has shown the tea party-backed Mourdock closing in recently.

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."

Mourdock, however, chose a more direct answer that hit on key words and talking points popular with the tea partiers pushing his candidacy.

Much of the debate focused on questions of foreign policy, Lugar's clear strength. Mourdock, though, challenged why Lugar didn't support sanctions proposed by Arizona Sen. Jon Kyl against such countries as Iran, North Korea and Syria.

"It's something that Sen. Lugar, last I knew, was still opposing," Mourdock said. "He wanted to do that through the U.N. I think there are times we need to act unilaterally to put the pressure on those nations to make sure they understand they know we care about world peace and we don't want to see those nations develop nuclear arms."

Lugar said he works daily with Kyl and that the United States leads in trying to prevent Iran from developing nuclear capabilities.

"The real problem is making sure we get the Russians aboard, we get the Chinese aboard, we get others aboard who right now are undercutting those efforts," Lugar said. "That's going to require some very strong diplomacy."

Until this week, the Lugar team had spent most of its money attacking Mourdock for his attendance at state boards, alleging that he doesn't personally attend enough meetings, and attacking President Barack Obama for blocking construction of the Keystone XL oil pipeline out of Canada. But Lugar began the week airing a statewide ad accusing Mourdock of leaning too heavily on "D.C. outsiders" to carry him through the race.

Mourdock struggled occasionally when 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.

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 Obama's Supreme Court nominees.

Before the debate, a couple dozen Lugar supporters and opponents lined the street yelling and waving signs as cars drove by.