Lugar says he wants to see a Republican majority in the Senate but will not campaign for Mourdock.
Political thinkers believe the party which can best energize voters may have an edge in November's U.S. Senate race.
Sen. Dick Lugar is most known for his contributions to foreign policy.
Mourdock says he’s not willing to compromise his principles.
Richard Mourdock beat Sen. Richard Lugar by a substantial margin Tuesday.
Senator Dick Lugar conceded to Richard Mourdock in a primary-night speech Tuesday.
Indiana Treasurer Richard Mourdock has defeated U.S. Senator Richard Lugar in the Republican primary.
Richard Lugar and Richard Mourdock have run a fierce campaign against each other. The results of the campaign will come during Tuesday's primary.
Some Republicans say a mailer in support of Senator Richard Lugar encourages Democrats and independents to vote in the Republican primary.
The bill would end six-day mail delivery, close post offices and begin to phase out door-to-door delivery entirely.