Patrick recently said he worries about how Clinton is being viewed as the inevitable nominee, but he hasn't made any moves of his own to suggest he's running. But if he could put a credible team together, he'd be a much more threatening challenger than, say, Maryland Gov. Martin O'Malley.
3. Sen. Claire McCaskill of Missouri
In a normal year, a female media-savvy, red-state prosecutor who defied the odds to win a second term in the Senate would be at the top of many Democratic wish lists. But like Kaine, this early Obama supporter was one of the first elected officials to sign up with Clinton's nascent campaign, taking herself out of the conversation. Part of her motive was to ingratiate herself with Team Clinton, who placed McCaaskill on Hillary's "enemies list" after she said she didn't want her daughter near the former president in a Meet the Press interview (as an Obama surrogate).
Instead of sucking up to the Clintons, why not challenge Hillary? Representing a populist state, McCaskill would be well positioned to challenge Clinton on her wealth, ties to corporations, and perceived disconnect from the middle class. Plus, McCaskill's long-term prospects in the Senate aren't great, assuming she doesn't face Todd Akin again in 2018.
4. Former Sen. Russell Feingold of Wisconsin
Where have you gone, Russ Feingold? The former Wisconsin senator and campaign finance reform scold has virtually disappeared from the political arena. Like Clinton, he's now serving in the State Department — as the special envoy for the African Great Lakes region and the Democratic Republic of the Congo.
Like Elizabeth Warren, Feingold would be able to rally progressives around his campaign but he could potentially have more appeal to male voters, a demographic where the party has gotten crushed in the Obama era. Unlike Clinton (and Warren), Feingold took a lone stand for same-sex marriage in 2006, when most elected Democrats opposed such legislation. He's been a longtime critic of outside groups' campaign spending, which has been a rallying cry for liberal Democrats in the age of the super PAC.
Feingold has always marched to the beat of his own drum, and it would be hard to see him prevailing over the better-organized Clinton. But he could persuasively assert he was ahead of the curve on the issues animating today's Democratic Party, a powerful argument for the grassroots base. Indeed, he'd be in a situation similar to that of another reform-minded former Democratic senator, Bill Bradley, who challenged a sitting vice president and nearly won the New Hampshire primary.
5. Missouri Gov. Jay Nixon
Winning two terms in an increasingly Republican red state — he ran 9 points ahead of Obama in 2008 and 11 points ahead in 2012 — Nixon is one of the most accomplished Democratic governors in the country. The Kansas City Star's Steve Kraske dubbed Nixon the "Teddy Roosevelt of Missouri — vigorous, a champion of the outdoors, constantly touring all corners of the state more than any chief executive in state history." He worked with Republicans to pass comprehensive jobs legislation, cut spending, and passed ahead-of-the-curve legislation incentivizing college graduates to specialize in high-demand health care fields. Nixon won high praise for his handling of the aftermath of the tornadoes that devastated Joplin. And he's won over some social conservatives by allowing restrictions on late-term abortions and reducing the age for residents to purchase a concealed-weapons permit. But he's also expanded Medicaid and focused on boosting spending for education.