Barack Obama and Hillary Clinton, the two frontrunners for the Democratic presidential nomination, will face off in their 20th debate, this time smack dab in the Heart of It All. Analysts with both camps insist that the Ohio primary on Tuesday, March 4, is crucial to win the nomination, as candidates remain mired in a close struggle. [Obama count] [Clinton count]

The debate will air tonight at 9 p.m. on NBC and MSNBC. The 90-minute showdown is being sponsored by Cleveland State University. The Ohio News Network (ONN) will air a pre-debate special at 8:30 p.m. and a postmortem immediately afterward, at 10:30 p.m. Both programs will feature commentary and analysis by political leaders. [Full story]

You'll likely hear more about national health care, arguments over support for the Iraq war and recurring discussions of global trade, which has become a main centerpiece for both campaigns. That's not surprising, as millions of manufacturing and industrial jobs once headquartered in Ohio have gone overseas. The two have softened their talons in recent weeks -- before you could feel the hate between them -- but Clinton can't win without Ohio, so she'll be ready to stand up and take some shots.

Dispatch reporter Alan Johnson compiled these viewing tips from experts.

Listen actively. Switch from passive, entertainment mode to learning mode. Pay attention.

Focus on substance, not style. The candidates' clothes, facial expressions and hair style aren't too important. Their plans and policies are.

Ignore diversionary tactics. Candidates try to divert attention by attacking the questioner, or by relying on dismissal, digression and obfuscation. Focus on issues important to you.

Keep an open mind. Set aside personal political biases as much as possible.

Turn off the TV when it's over. The spin zone and post-debate analysis are designed to influence you. Make up your own mind. [More]

Bonus: Both candidates are using the "flip-flopper" tag to discredit opponents, so you're going to hear each call the other out on some issues. The Washington Post ran this piece about the biggest flip-flops made by Obama and Clinton.