Republican U.S. Sen. Richard Lugar is attacking President Barack Obama — turning his one-time mentee into a key target — and showing himself with former President Ronald Reagan in his first campaign ad in what will likely be a tough re-election contest.

Lugar called Obama "wrong" on job growth in the ad that is set to start airing Wednesday across Indiana. The ad is set to air July 20 to July 29 in major markets including Indianapolis, Evansville and Fort Wayne. The Lugar campaign would not say how much it spent on the ad.

Conservatives have lambasted Lugar as "Obama's favorite Republican" for siding with the president more than other members of the GOP.

The anti-tax Club For Growth spent about $150,000 airing ads against Lugar across the state, in the same markets, that began airing last week. The conservative group paid for ads attacking Lugar for supporting the bank and auto bailouts.

Lugar noticeably ignores his opponent, state Treasurer Richard Mourdock, in the new ad. He also used about a quarter of the 30-second spot to show himself with Reagan.

"For 35 years, I've battled for balanced budgets and less government. I've helped beat tough times before. And we can do that again," Lugar says in the spot. "I hope you'll agree that a veteran, fighting alongside our new recruits, will help."

Lugar's campaign advertising director Mark Lubbers said Lugar wanted to focus on economic development and job growth rather than targeting politicians. He said Lugar has routinely opposed Obama on economic issues.

But in a Senate Republican caucus that has stood almost squarely against Obama since the president took office in 2009, Lugar has been one of only a handful of senators to break ranks with his party on some issues, including supporting the nuclear arms treaty with Russia signed by the president in February.

Obama leaned heavily on Lugar's foreign policy credentials when campaigning in 2008, featuring the Republican senator in a campaign ad that focused on their work together to curb nuclear arms proliferation. The two worked together on the Senate Foreign Relations Committee starting from when Obama joined the Senate in 2005.