There are supposed to be three things in life that are certain: death, taxes and Hillary Clinton being the Democratic nominee in 2016. But what if the former Secretary of State decides not to run? There are a number of other Democratic hopefuls already publically hinting at their own bids for the Oval Office. Here are six of the most prominent politicians considering a run or having their names floated.

Joe Biden

As an incumbent Vice President, Joe Biden would have a number of built-in advantages in a presidential bid. He would already be a national figure with high name identification, built-in fundraising networks and would essentially be a quasi-incumbent—after all, the last sitting Vice President to ponder a presidential campaign and fail to win his party’s nomination was Alben Barkley in 1952. Biden also has a strong core of support in Iowa based on two previous presidential bids. However, Biden has a number of significant weaknesses. If elected, he would take the oath at the age of 74, making him the oldest man inaugurated in American history, surpassing Ronald Reagan who was 73 when sworn in for his second term in the Oval Office. Biden also has a reputation for being gaffe-prone and politically undisciplined, traits that have often caused political heartburn in the past.

Martin O’Malley

O’Malley has been a successful two-term Governor of Maryland and previously served as Mayor of Baltimore. He’s already making visits to key early states like New Hampshire and trying to build a national profile. O’Malley casts an appealing figure to Democratic primary voters. He’s a relatively young Irish Catholic (important in states like Iowa and New Hampshire) with a long list of concrete accomplishments from his time in the Maryland State House. However, O’Malley, a longtime Clinton ally still faces a couple of obstacles even if Hillary doesn’t run. Marylanders have been uniquely unsuccessful in bids for national office—the last Maryland resident to ever receive an electoral vote was William Wirt of the Anti-Masonic Party in 1832. Furthermore, O’Malley is still relatively unknown nationally and may be most associated with Tommy Carcetti, a controversial character from The Wire, who was loosely based on him.

Howard Dean

Howard Dean is still best known for his failed 2004 Democratic primary campaign that ended for all intents and purposes when he screamed after finishing a weak third in the Iowa Caucuses. However, the former Vermont Governor and DNC chair has been making noises about mounting a long-shot bid in 2016. If he ran, Dean would likely try to fill the same niche on the left of the field that he occupied in 2004. However, the Democratic Party has since moved past many of Dean’s positions. He appealed to liberals in 2004 on his opposition to the Iraq War, his support for civil unions and his efforts to expand health care in Vermont. A decade later, all three issues have lost their salience. The best-case scenario for Dean would be a campaign as successful as George McGovern’s failed efforts to recapture the magic of 12 years earlier in 1984.

Brian Schweitzer

The former Montana Governor may have passed on a bid for an open Senate seat earlier this year but he’s still making noises about running for President in 2016. Since leaving office, Schweitzer has become a cable news fixture as a pundit, including an appearance on MSNBC in late November where he stated that one of his life ambitions is to visit every county in Iowa. Schweitzer is a brash, outgoing politician who achieved remarkable success in the relatively red state of Montana. However, some of the traits that enabled Schweitzer to succeed in Montana may hurt in a Democratic presidential primary. In particular, his strong opposition to gun control may not play well with liberal voters in the post-Newtown era as well as his longstanding support for the coal industry, a major Montana employer. On the flip side, his support for gay marriage and single payer healthcare may not endear to those remaining conservative Democrats who might be attracted to Schweitzer based on his support of gun rights. Schweitzer will also be tested as someone who previously has only run in the relatively safe confines of Montana, where campaigns are relatively cheap and has never had an opponent do serious opposition research on him. To be a successful national candidate, Schweitzer would need to fundraise on far more significant scale than he ever has before and answer questions about why he suddenly and dramatically backed out of his Senate bid earlier this year.

Andrew Cuomo

The New York Governor has long been considered a contender for 2016 only if Hillary Clinton doesn’t run. After all, both have relatively similar political and donor bases in New York. But, despite those similarities, not to mention carrying famous political names, the two cut very different political profiles. While Clinton is considered a role model and icon among many women, Cuomo, who started his career in public life as the political enforcer for his father, former New York Governor Mario Cuomo and has rarely inspired ideological devotion. Cuomo, who is proudly a centrist Democrat in the tradition of Bill Clinton, may run into issues with Democratic primary voters over his battles with public employer unions in New York, which doesn't exactly poll well with liberals. However, Cuomo has never been accused lacking ambition or a will to win. Whatever his weaknesses with voters in states like Iowa and New Hampshire, he will put in time and spend the money necessary to give him a chance to win. It’s just a question whether liberal Democrats in Dubuque, Iowa could ever embrace a centrist from Albany.

Elizabeth Warren

Almost every liberal skeptical of Hillary Clinton’s progressive bona fides wants Elizabeth Warren to run for the President. There is one clear exception though, Elizabeth Warren. The first term Massachusetts Senator’s disavowals of interest in seeking the Oval Office have been almost Shermanesque. She even signed a letter with every other female Democratic senator urging Hillary Clinton to run but that hasn’t calmed the speculation. Warren was a hero to Democrats long before she was elected to the Senate because of her work trying to reform bankruptcy laws and set up the Consumer Finance Protection Bureau. But, with her election in 2012, it has magnified her celebrity with her work pushing for administrative reforms in the SEC and pointed questions in Senate hearings. If she runs, Warren has the support and the star power to be a formidable force in a Democratic primary. The problem is that, at least as of now, she doesn’t seem to have slightest desire to mount a bid for the Presidency.