A new Howey/DePauw Indiana Battleground Poll shows Indiana state Treasurer Richard Mourdock with a ten-point lead over Sen. Dick Lugar in the state's May 8th Republican primary.

Mourdock beats Lugar 48 percent to 38 percent in the bipartisan independent survey, taken Monday and Tuesday of this week.

U.S. Senate candidates running in the GOP primary, Sen. Richard Lugar, R-Ind.,and Richard Mourdock, right, participate in a debate Wednesday, April 11, 2012, in Indianapolis. (Darron Cummings/AP)

In Howey’s last poll, taken March 26 to 28, Lugar led Mourdock 42 percent to 35 percent. Since then, outside groups supporting Lugar have ended their commitments, while groups backing Mourdock, including the anti-tax Club for Growth, have continued to pummel the six-term senator.

According to the poll, the likely primary voter pool skews to the right: it is 44 percent very conservative, 33 percent somewhat conservative and 19 percent moderate. While Lugar has a wide lead with moderates, Mourdock takes the larger pool of very conservative voters.

Some Republicans have encouraged Democrats and independents to vote for Lugar in the open primary. The pollsters called some general election voters who had not voted in Republican primaries before, but they found that few planned to participate and those that did

Sixty percent of the Republican primary voters in the poll want a senator “to focus first on trying to solve many of our country’s problems, even if that means working with elected officials across the aisle to do it.”

Yet Lugar, under fire for his bipartisan record, still loses out with those voters to Mourdock, a staunch conservative.

Republican pollster Christine Matthews of Bellwether Research and Fred Yang of Garin-Hart-Yang Research Group surveyed 700 likely primary voters. The poll’s margin of error is plus-or-minus 3.7 percentage points.