Grover Norquist to endorse Mourdock after Lugar rejects no-tax pledge

— --
Grover Norquist, the influential conservative activist who is the president of Americans for Tax Reform, will endorse Richard Mourdock over Dick Lugar before next week's Republican Senate primary in Indiana, Yahoo News has learned.

Lugar, who has represented Indiana in the U.S. Senate since 1977, has never signed Norquist's " Taxpayer Protection Pledge" never to raise taxes. A majority of Republican lawmakers--and some Democrats in conservative districts--have signed the Americans for Tax Reform pledge.

Norquist will join a handful of high-profile conservatives and organizations--including Sarah Palin and the American Conservative Union--who have backed Mourdock, Indiana's state treasurer who is running to Lugar's right with the backing of national tea-party groups.

Members of Lugar's congressional staff met with Norquist at the Americans for Tax Reform headquarters in Washington earlier this year to discuss whether Lugar would sign the no-tax pledge, a source who attended the meeting told Yahoo News.

Norquist never received a reply from Lugar's staff, the source said, so he contacted Lugar's office last week to give the Indiana senator one final chance to sign. Lugar refused, the source said.

A spokeswoman from Lugar's Senate office did not immediately return a request for comment from Yahoo News.

Norquist plans to announce the endorsement on a conference call with Mourdock, who signed the pledge, on Wednesday afternoon at 2 p.m. ET, Adam Radman, a spokesman for Americans for Tax Reform, told Yahoo News.

More popular Yahoo! News stories:

• What Robert Caro's LBJ biography 'The Passage of Power' could teach Obama and Romney

• Jeff Greenfield on why 2012 election predictions are rubbish: Fear the Black Swan!

• Romney meets with Michael Bloomberg in hopes of landing endorsement

Want more of our best political stories? Visit  The Ticket or connect with us  on Facebook, follow us on Twitter, or add us  on Tumblr. Handy with a camera? Join our  Election 2012 Flickr group to submit your photos of the campaign in action.