Sen. Dick Lugar (R-Ind.) and his GOP challenger, Indiana state treasurer Richard Mourdock, each released new attack ads Monday, with Lugar accusing his rival of selling out to "outsider groups" and "Mickey Mouse attacks," and Mourdock attacking Lugar on gas prices.

"Hoosiers need leaders who fight for us, but Richard Mourdock's already sold out to D.C. outsider groups, running his campaign on the backs of their money, and Mickey Mouse attacks,” says the narrator in Lugar's ad, quoting an editorial in The Wall Street Journal and accusing Mourdock of selling out.

Watch Lugar's ad:

Mourdock's ad accuses Lugar of trying to raise gas prices.

"Dick Lugar wanted to raise gas taxes a dollar a gallon. That’s right. Lugar wanted us to pay an extra dollar for every gallon of gas. That’s outrageous," the narrator says, referring to a 2009 column Lugar wrote advocating for a "tax shift" from payroll taxes to gas taxes.

Watch Mourdock's ad:

The battle between Lugar and Mourdock has become increasingly bitter in recent weeks. Indiana's primary is May 8.

10 more election stories from beyond the presidential field:

Kaine Touts Fundraising In Expensive Virginia Senate Race [CNN]

Charlie Rangel Gets Congressional Challenger [The New York Times]

Donald Rumsfeld Fundraising For North Carolina Congressional Candidate Ilario Pantano [Politico]

Aaron Schock Denies Using Campaign Funds For Fitness Program [Fox News]

Montana Senate Candidates Questioned Over Campaign Finances [AP]

Doris Kearns Goodwin's Son Launches State Senate Campaign [Boston Globe]

Measure To Scrap Public Financing Off Arizona Ballot [Arizona Daily Sun]

Scott Brown Donates To Charity Under 'People's Pledge' Discouraging Third-Party Ads [HuffPost]

Steve King: Marco Rubio ‘Speaks To My Heart’ [The Washington Post]

Republicans, Democrats Take Shots In Heated California Primary [Los Angeles Times]