While Tuesday’s first Democratic presidential debate will probably lack the name calling and sharp jabs of the Republican faceoffs, there’s still potential for strong disagreements between the party’s leading contenders.

On the trail, Hillary Clinton and Bernie Sanders shy away from direct mentions of each other, focusing instead on the Republicans.

But on Tuesday it will be hard to escape the fact that they have had very different approaches to major issues.

Former Maryland Gov. Martin O’Malley has been introducing himself to voters for months, but he still is almost nowhere in the polls. The debate could be his chance to grab the kind of attention that could get his candidacy off the ground.

Joining O’Malley at the bottom of the field are former Virginia Sen. Jim Webb and former Rhode Island Gov. Lincoln Chafee.

And then there’s Joe Biden, the man who could throw a wrench in the whole thing — if he decides to run.

The event in Las Vegas, hosted by CNN, is one of four Democratic debates scheduled.

Meet the candidates

Lincoln Chafee

Chafee — who doesn’t register in some polls — served as Rhode Island senator from 1999 to 2007 and then as the state’s governor from 2011 to last January. A liberal Republican, Chafee was often ranked as the least conservative Senate Republican.

Hillary Rodham Clinton

Clinton, former first lady during her husband Bill Clinton’s administration in the 1990s, was elected to the U.S. Senate from New York in 2000. President Obama named her secretary of state after their bruising battle for the presidential nomination in 2008. She had been the prohibitive favorite until recently, but has been dogged by questions about her e-mail use as secretary.

Martin O’Malley

O’Malley served as Maryland governor from 2007 to this year and Baltimore mayor before that. O’Malley — known for his gun control push and cap-and-trade carbon emissions policy as governor —has been pushing for more debates.

Bernie Sanders

He became Vermont’s at-large congressman in 1990, serving for 16 years before being elected to the U.S. Senate in 2006. A self-described socialist, Sanders — who has been drawing huge crowds on the campaign trail — has been particularly vocal on the issue of income inequality.

Jim Webb

The former one-term Virginia senator, who has been running a very low-key campaign, also has served as secretary of the Navy. He was awarded the Navy Cross for heroism in Vietnam.

And then there’s … Joe Biden

The vice president, who represented Delaware in the Senate for 36 years, ran for the Democratic presidential nomination in 1988 and 2008, when Barack Obama chose him for the ticket. His son Beau died of cancer this year; he’s giving mixed signals about whether he plans to join the 2016 race.