By Bill Scher - August 18, 2014

There is a wariness of Hillary Clinton in some corners of the left.

"Will Hillary be with Wall Street like she's been all along?" asks the executive director of Democracy for America. "Generalissima Hillary Clinton," scoffs Ralph Nader—and that was before her hawkish interview with The Atlantic. Clinton’s skeptics want her to face a primary challenger, if not to defeat her then to apply enough left-flank pressure so she will not have an incentive to drift rightward in the general election (or as president). Strangely, they are ignoring someone who is already auditioning for the role of progressive populist challenger, and who has the chops to back it up: Sen. Bernie Sanders of Vermont.

Left-wing Democrats pine for Sen. Elizabeth Warren. But she has emphatically said she is not running, nor is she doing anything prospective candidates have to do to prepare to run, like visit early primary states.

Sanders is practically identical to Warren when it comes to the issues progressive populists care about—and where they consider Clinton squishy. He wants to break up the big banks so they can’t be “too big to fail.” He wants to see bankers responsible for the 2008 crash thrown in jail. He was one of only four senators, including Warren, to oppose President Obama’s nominee for U.S. trade representative in protest of the White House’s push for regional trade agreements with Europe and Asia. He would increase, not cut, Social Security benefits.

For liberals who consider Clinton suspect on military matters, Sanders voted against the most recent defense spending bill, saying it was another “bloated military budget.” Warren, who represents a state with six military bases, voted for it.

Sanders holds an even bigger advantage over Warren: He’s actually interested in running.

Unlike Warren, he has used the phrase “I’m running,” as when he told the Huffington Post, “I’m running to talk about the issues that impact the working class of this country and the middle class.” Unlike Warren, he has met with voters and activists in Iowa and New Hampshire, and has three Iowa town-hall meetings scheduled for next month.

Furthermore, Vermont’s junior senator has long been a nationally known favorite in progressive circles. For years he has held court in weekly “Brunch With Bernie” segments on Thom Hartmann’s national radio show. He even can tout his ability to work across the aisle, having recently negotiated bipartisan deals to reform the Veterans Administration and audit the Federal Reserve.

Yet when Sanders teases a presidential run on CNN or MSNBC or ABC, he is largely greeted with silence from his progressive brethren. There are isolated voices of encouragement: the Progressive Democrats of America, The Nation’s John Nichols, The New Republic’s Michael Kazin. But nothing that resembles the enthusiasm generated by everyone’s favorite non-candidate, Warren.

What gives? Why is the left ignoring the option – the only option, really – that’s right under its nose?

Sure, it is implausible that a self-described “socialist” with a gruff Brooklyn demeanor could actually win. But as the Washington Post reported last month, "Even Clinton’s skeptics acknowledge the difficulty of derailing her juggernaut," so their hope is that a primary challenge can "shape the debate and pull Clinton to the left on issues.”

Sanders, who has stressed that he would “not [be] running to attack Hillary Clinton,” is perfectly suited to play that role. A Clinton-Sanders primary – assuming Sanders could generate enough support to force Clinton to engage – would be serious debate over the issues progressives care about, not a personality clash with scorched-earth attacks that could weaken the eventual nominee for the general election.

Apparently, the reason for the lack of interest lies in progressives’ collective hunger for The Next Big Thing. For the economic populists, Warren’s mix of Okie folksy charm and Harvard intellect is a fresh face that can expand their gospel beyond the already converted. Sanders may have a case to make that he has real experience building ideologically diverse coalitions around populist issues. But today’s Vermont is so deep blue, people have forgotten than Vermont was much more Republican when he first won statewide in 1990.

For leftists more interested in opposing war and government surveillance, Sen. Rand Paul is the Next Big Thing. Nader, for example, has been more interested talking up Paul’s prospects for building a left-right coalition against Clinton than promoting Sanders (though that could be because Nader has publicly complained that Sanders doesn’t return his phone calls).

But for most on the left, Paul’s libertarianism is a bridge too far. And for Warren, a presidential run is a bridge too far. Sooner or later, progressives who want a primary challenge from the populist left will realize that their choice is Sanders or nobody.

The risk for them is that they will come to that conclusion too late.

As Yahoo! News reported, the one thing that would stop Sanders from taking the plunge is a lack of grassroots support and infrastructure. In Sanders’ words, “It's easy for me to give a good speech. … It is harder to put together a grassroots organization of hundreds of thousands … of people prepared to work hard and take on the enormous amounts of money that will be thrown against us.”

If the grassroots doesn’t show up for Sanders soon, he may decide that a run wouldn’t make enough of an impact to be worth the trouble. In other words, pine for Warren too long, and you may get no progressive primary challenge at all.