THE biggest heavyweight debate bout of the cycle looms Thursday.

The contender: a once unknown, very conservative Republican former state lawmaker, Sharron Angle. She was powered to the Nevada U.S. Senate nomination by out-of-state Tea Party Express PAC money.

The incumbent, a former boxer and current U.S. Senate Majority Leader Harry Reid, one of the least popular politicians in America.

The setting for this rhetorical rumble; Las Vegas of course, where the polls are tied and unemployment (14.4 percent) is the worst in the country.

There ain't no marquis of queensbury rules for this one, they will kick, scratch and hair pull like a WWE event (but this is not the Connecticut Senate race.)

Nevada polls suggest a dead heat. This debate may prove decisive.

Angle needs a breakout moment, one that reveals how liberal, entrenched and ossified she says Reid has become...and she can't afford ANY major gaffes.

Reid hopes to humiliate Angle with knockdowns on policy then frame her as a Tea Party extremist.

It's a 60-minute matchup on local TV in Nevada and C-SPAN nationwide.

Angle must appear informed, in command, and avoid the kind of hyperbole that has brought her some ridicule even from Republicans. She's also got to reasonably explain how she has tempered some of her more conservative views since the GOP primary without appearing inconsistent. Reid has been cutting her up on this lately and will surely come after her as a fringie flip-flopper.

This may be her last best chance to persuade voters why they should oust the powerful majority leader and elect her instead.

Reid is seeking a 5th term. His problems are multiple and huge. He must convince Nevadans he is still one of them, and not out of touch despite decades of deal-making in Washington. He'll have to re-explain ramming thru on largely party-line votes the healthcare reform, the stimulus packages, the bailouts, and on and on.

Reid's 70 yrs old. He has way more debate experience from past campaigns than Angle.He'll need to avoid getting too angry with the 61-year old Angle, who'd love to make Reid lose his temper.

In recent weeks there have been angry scuffles at a handful of Senate campaign events in Nevada. Outside the debate Thursday the demonstrations will be raucous, security is being beefed up in anticipation of rowdies on both sides.

Early voting starts Saturday in Nevada.

About half the Silver State's votes will be cast before Election Day.

Carl Cameron currently serves as Fox News Channel's (FNC) Washington-based chief political correspondent. He joined FNC in 1996 as a correspondent.