Des Moines, Iowa -- The three remaining Democratic presidential candidates will face off at 9 p.m. tonight for two hours in a debate televised live on CBS from Drake University.

It is the second debate in the contest and pundits far and wide say it's a crucial moment in the campaign. Here are few things to watch:

1.  What do the candidates say about Paris? CBS News has said it will shift tonight's focus from domestic issues to security, at least at first, the Los Angeles Times reported.  All three used Twitter to express outrage about the attacks late Friday, although Hillary Clinton issued a statement vowing to "wage and win the struggle against terrorism and violent extremism." Expect moderators to -- hopefully -- get the candidates to say what, exactly, they would do if they were in the White House on Friday.

2. Is this Bernie's last stand? We have a story in today's print edition that wonders as much. and most eyes will be on U.S. Sen. Bernie Sanders, I-Vermont, tonight. After rallying over the summer, the colorful candidate has seen Hillary Clinton build a commanding lead again. Sanders and former Maryland Gov. Martin O'Malley must hope Clinton stumbles.

3. Do the two men gang up on the woman?  The New York Times thinks Sanders might go on the attack tonight, but only if prompted. The first Democratic debate was decidedly genteel, with Sanders even defusing one of the biggest areas of attack against Clinton -- her emails. But, even if Sanders and O'Malley go on the offensive, Clinton has proven she can take it.

4. Will anybody watch? The website Vox.com has pointed out that Saturday debates are rare. Of 100 debates since 2000, only seven have been on a Saturday. (Thursday is the most popular day for debates, by the way.) And as The Daily Kos pointed out, the Democratic National Committee might have scheduled the debates so fewer people would see them.

5. How local do the questions get? Two of the four questioners are Iowa-based journalists. If Sanders or O'Malley have an opening, it could be to position themselves contrary to Clinton on Iowa-centric questions. Sanders has already come out against the Bakken pipeline proposal, which would run an oil pipeline across the state from North Dakota to Illinois. Clinton has yet to take a position.