If Hillary Rodham Clinton passes in 2016, which Democrats run? The Fix ranks the tiers. Warren (D-Mass.) has been adamant about her lack of interest in the race. But things change in politics. Sen. Barack Obama of Illinois was similarly adamant about his lack of interest in running for president in 2008 - and we know how that turned out. The simple fact is that Warren's beloved status among rank-and-file Democrats - and an elite group of very wealthy and very liberal major donors - means that if Clinton doesn't run, Warren will come under a significant amount of pressure to reconsider. And Warren would have a built-in excuse to explain her past comments: "Well, I never thought about it seriously, because I expected Hillary to run. But now that she's not . . .  Because of that upside - with apologies to NBA draft experts - we are moving Warren into our second tier of potential Democratic presidential candidates. Clinton remains as the lone candidate in the first tier - a space she will occupy until she announces whether she is running. Our breakdown of the field is below. The candidates within each tier are listed alphabetically. Tier 1 (If she runs, the other tiers don't matter) Hillary Clinton: Everything we hear privately and everything we see publicly suggests that Clinton is running - or at least allowing those around her to put the pieces in place to be ready if/when she flips the switch. Does that mean she is definitely in? But it means that with every passing month, we become more and more convinced that the surprise announcement would be that she's not running. Tier 2 (If not Hillary, then . . .) Joe Biden: Last week, the vice president called state Rep.-elect Brian Meyer (D) to congratulate him on his special-election victory a few days earlier. Why would the VP call a not-even-sworn-in-yet state legislator? Because Meyer is from Iowa. And that tells you everything you need to know about whether Biden is thinking about running for president in 2016. Andrew Cuomo: Unlike some of the other people on this list - Martin O'Malley, we are looking at you - the New York governor is doing the do-as-little-as-possible-to-stoke-2016-speculation thing. That may or may not be a thing. Cuomo, the scion of a famous political family, knows that in a field without Clinton, he is a heavyweight given his name, fundraising abilities and résumé as governor of one of the most Democratic states in the country. Martin O'Malley: The governor of Maryland is, without question, the candidate most open about his interest in running for president. "By the end of this year, I think we're on course to have a body of work that lays the framework for a candidacy in 2016," O'Malley told reporters in August. His travel schedule is heavy on trips to Iowa, New Hampshire and South Carolina, and O'Malley used his time as chairman of the Democratic Governors Association to build out his national fundraising network. Elizabeth Warren: See above. There's no one not named Clinton on this list who combines the star power and fundraising potential that Warren boasts. And, Warren has one thing that even Clinton doesn't: a rabid following within the liberal base of the party. Tier 3 (There's a will and a way - sort of) Kirsten Gillibrand: Gillibrand is a sneaky-good politician. Without all that much fanfare, the senator from New York has turned herself into a liberal champion. She's also someone who has proved that she knows how to raise money; she took in $30 million between her 2010 and 2012 Senate campaigns. Tier 4 (There's a will but - probably - not a way) Howard Dean: The former Vermont governor clearly looks back on his one-time front-running 2004 presidential campaign wistfully and wonders whether he could catch lightning in a bottle again. The answer is almost certainly no, but Dean, never someone who cared much about the party establishment's opinion of him, might be the sort of person who would be willing to wage a campaign against Clinton from the ideological left. Amy Klobuchar: The field above her is too crowded for the senator from Minnesota to take a flier on a presidential bid. But she has the résumé and the ambition to surprise people if things were to break just right.