The website Howey Politics Indiana reported Thursday that its poll conducted with DePauw University shows U.S. Senate candidates Joe Donnelly and Richard Mourdock in a virtual tie about six weeks before the Nov. 6 election.

The Howey/DePauw Indiana Battleground Poll had Democrat Donnelly favored by 40 percent of poll respondents, compared with 38 percent who favored Republican Mourdock and 7 percent who supported Libertarian Andrew Horning.

The spread between Rep. Donnelly, D-2nd, and state Treasurer Mourdock is within the plus-or-minus 3.5 percent margin of error.

The survey of 800 likely voters was taken Sept. 19 to 23 by Republican pollster Christine Matthews of Bellwether Research and Democratic pollster Fred Yang of Garin-Hart-Yang-Research, according to Howey Politics Indiana.

The same poll had Republican presidential candidate Mitt Romney leading President Obama 52-40 and GOP gubernatorial candidate Rep. Mike Pence, R-6th, leading Democratic candidate John Gregg 47-34, with Libertarian candidate Rupert Boneham favored by 5 percent of respondents.

The Senate race numbers are in keeping with a poll conducted in late July by the independent polling firm Rasmussen Reports. In that survey, which had a plus-or-minus 5 percent margin of error, Mourdock had 42 percent and Donnelly 40 percent.

A Howey/DePauw poll taken in advance of the May 8 Republican primary election showed Mourdock leading six-term Sen. Richard Lugar by 10 points. Mourdock defeated Lugar by 21 percentage points.

Meanwhile, the non-partisan Indiana Debate Commission announced Thursday that campaign representatives for Mourdock, Donnelly and Horning have signed an agreement for the candidates’ participation in two previously announced debates.

The debates will be at 7 p.m. Oct. 15 at WFYI-TV in Indianapolis and at 7 p.m. Oct. 23 at Indiana University Southeast in New Albany.

The debate commission is soliciting questions for the candidates at indianadebatecommission.com.