NEW YORK (CNN) — It's certain to be long night, but here are some early indicators I'll be keeping my eye on as the first wave of exit polls roll into the CNN Election Center.

The gender gap:
The bigger it is, the more it helps Hillary Clinton. She needs to do well with women voters tonight in order to carry Ohio and Texas. In nine Super Tuesday primary states Clinton won, men were split, but nearly 60 percent of women voters supported the New York senator. In seven states Obama won that night, the Illinois senator beat Clinton among both men and women.

Young voters
Much attention has been focused on Obama's ability to rally young voters. The number of these voters that showed up to vote and the proportion that break for Obama will be key to his chances of winning tonight. Senior voters have always been a backbone of support for Clinton, and will likely continue to be so today. In many of the states Obama has won, the youth vote has been heavy and has broken for him better than 2 to 1.

Minority turnout
Minority turnout will be crucial, but which minority? African-American voters have solidly aligned themselves behind Obama, and Latinos have usually supported Clinton. This means Obama has had the edge in states where African-American voters make up a significant proportion of the electorate while Clinton has had the advantage in states where Latinos do so. But Texas has both a heavy African-American population and a heavy Latino population. Whichever group has a higher turnout could be key to who wins the state.

Union workers
Whichever candidate wins among union voters in Ohio could very well carry the state. Even though several major unions in Ohio — like the Teamsters and the Service Workers and the Food and Commercial Workers — have endorsed Obama, the Nevada caucuses proved that union voters don't necessarily vote the way their leaders tell them to. Clinton is banking on strong support from this demographic to help her win tonight.

Independents
How much of a role will they play? Independent voters are allowed to vote in all four states today. In the past, these voters have strongly favored Obama. Will their turnout be high enough to tip the scales toward the Illinois senator tonight?

Republicans
Republicans are allowed to vote in the Democratic primary in Texas. Some conservative commentators, like Rush Limbaugh, are urging them to vote for Hillary Clinton just to keep the Democratic race going. The idea that large numbers of Republicans will vote for Clinton just to make trouble for the Democrats seems unlikely. But lots of unlikely things have happened this year.

Watch Bill Schneider break down the demographics of the March 4 primaries

Related: CNN's Ed Lavandera reports on early Texas voting

–CNN Senior Political Analyst Bill Schneider

(CNN) – A major ice storm is forecast for the northern half of Ohio as voters go to the polls to vote in a primary there that may determine Sen. Hillary Clinton’s fate and seal the GOP nomination for Sen. John McCain.

Dayton and Columbus will likely see some wintry weather but be spared the worst of the ice and sleet forecast for Toledo, Mansfield, Cleveland, Akron, and Canton.

The storm is projected to begin before polls open at 6:30 a.m. ET Tuesday morning and last much of the day, and there is a potential for widespread power outages in the region.

Heavy rain and thunderstorms are also possible in the southern part of the state, where flood watches are in effect.

Another state is expected to experience a primary day storm Tuesday: much of Vermont is likely to see winter weather Tuesday, with the heaviest snow, sleet, or ice expected in the afternoon.

After a stormy Monday in Texas, the Tuesday forecast calls for calm skies.

–CNN’s Dave Hennen and Martina Stewart

Obama stopped in Rhode Island Saturday.

PROVIDENCE, Rhode Island (CNN) — It was one week ago Sunday that Hillary Clinton stood in the rec center at Rhode Island College and mocked fellow presidential candidate Barack Obama for his campaign's theme of hope, saying Obama can't just "wave a magic wand and have the special interests disappear."

Now, this Saturday, the Illinois senator took that same stage and couldn't resist bringing up her comments, now immortalized on Web sites like YouTube.

"I think she was here, right?" Obama said toward the end of his stump speech. "She was saying 'Oh, you know, he thinks that the clouds will part and… [that] he's so naïve.'"

The room quickly erupted in "boos."

"Wait, wait, wait," he said.

"He thinks he can wave a magic wand," he continued, mocking Clinton's impression, "and suddenly everything will be great."

Obama then went in to his standard stump lines, saying it's true he "talks about hope a lot." He then defended his rationale in doing so.

Related video: Clinton mocks Obama

Related video: Obama mocks Clinton

–CNN Political Producer Chris Welch

(CNN) – Lincoln Chafee, a former Republican senator from Rhode Island, announced his endorsement of Sen. Barack Obama Thursday.

Chafee, who became an Independent after losing his U.S. Senate seat to Democrat Sheldon Whitehouse in 2006, told reporters he intends to vote for Obama in Rhode Island’s Democratic primary on March 4.

"I believe Senator Obama is the best candidate to restore American credibility, to restore our confidence to be moral and just, and to bring people together to solve the complex issues such as the economy, the environment and global stability," Chafee said.

Chafee served in the U.S. Senate as a Republican beginning in 1999 after being appointed to the seat previously held by his father John Chafee, who represented Rhode Island in the Senate from 1977-1999. Lincoln Chafee was elected to his father’s Senate seat in 2000 but lost a re-election bid in 2006. In 2007 Lincoln Chafee became an Independent.  Chafee is currently a Visiting Fellow at Brown University's Watson Institute for International Studies.

While serving in the Senate, he was known for his liberal views and for his opposition to the war in Iraq – a position he shares with Sen. Obama.

–CNN Associate Producer Martina Stewart