Tens of millions of dollars have gone into ads trying to sway voters in Ohio’s U.S. Senate race. And many are filled with ominous tones questioning whether either between Sherrod Brown and Josh Mandel can be trusted.

But Mandel ratched that up in the second debate last week.

“Senator, you are a liar.”

That drew some gasps from the audience. But Brown says he should have expected it.

“I’m surprised by nothing with his history. People don’t’ trust him to tell the truth … don’t trust him to run ethical campaigns.”

Mandel did not return a call for comment about tonight’s debate. But he is expected to continue the focus of the first two debates -- questioning Brown’s long tenure in Washington, his support for the health-care overhaul and his support for the bailout of the auto industry.

Brown says he’s proud of that bailout, that it saved tens of thousands of jobs in hundreds of companies in Ohio and elsewhere.

One topic is expected to arise tonight that was only a blip in the first two debates: Abortion.

Mandel lists himself as pro-life. Brown, who favors abortion rights, noted Mandel has included cases of rape and incest in his anti-abortion stand.

And his campaign underscored parallels yesterday between Mandel’s position and that of Indiana Senate candidate Richard Mourdock, who said he opposes abortion “even when life begins in that horrible situation of rape,” because “that is something that God intended to happen."

When a reporter questioned Mandel about that yesterday, Mandel would not comment, saying he needed to see Mourdock’s remarks.