Only weeks ago, the person regarded as the most popular non-Hillary Clinton Democrat presidential contender was über progressive Sen. Elizabeth Warren (D-MA). Warren, however, told the “Today” show this week, “No. I’m not running, and I’m not going to run.” Perhaps that’s pol-speak for “Let me see what happens.” After all, if Clinton wins the nomination, Warren may be on the bottom of the ticket. Other challengers include, no kidding, Joe Biden, as well as Sen. Bernie Sanders (Socialist-VT) and former Virginia Senator Jim Webb.

But another contender waits in the wings, indicating every way but smoke signals that he’s plotting a run. He has yet to form the usual “exploratory committee,” though his intentions are clear.

Former Maryland Gov. Martin O'Malley appeared with George Stephanopoulos on ABC’s “This Week,” where O'Malley declared the nation needs “new leadership,” slyly implying that Hillary isn’t it. “History is full of times,” he continued, “when the inevitable frontrunner is inevitable right up until he or she is no longer inevitable.”

A little later O'Malley said, “Let’s be honest here. The presidency of the United States is not some crown to be passed around between two families.” Hedging lest he overstep, he added, “any two families.” As if there are any besides the Clintons and Bushes currently in that category.

Many Democrats have been hoping for a non-Hillary candidate for some time. Surveys find a majority of Democrats want Hillary to run against strong primary competition. And New Hampshire Democrat Party chairman Ray Buckley said he “fully anticipate[s] … a very robust primary.”

But those feminist-for-Hillary roots (and claws) go deep, and, on the same “This Week,” O'Malley was warned about ruining Hillary’s chances.

Jennifer Granholm, former Michigan governor and senior adviser to Ready for Hillary PAC, said Hillary “is comfortable enough to withstand a primary.” But Granholm perhaps isn’t so comfortable. She followed up, “And Martin O'Malley … I was thinking he might make a nice member of a President Clinton administration, so he better watch it.”

“I think he and anybody else – she would welcome into the mix,” Granholm continued. “That would be healthy. But I also think ultimately, she’ll be the next president.” Typical. Feminists want it all without working for it.

At this point, O'Malley may be Hillary’s foremost challenger, as scary as it might be for him.

O'Malley’s first major political venture was the mayoralty of Baltimore. Winning it in 1999 was considered quite a coup since Baltimore is a majority-black city. His platorm included decreasing the crime rate, increasing performance in public schools and improving health care delivery. What he actually achieved is a matter of dispute.

To reduce crime, O'Malley adapted New York City’s COMPSTAT accountability program for Baltimore, calling it CitiStat. Every call received by law enforcement is entered into a database that is regularly analyzed in “accountability sessions.” Good results win praise, bad ones bring trouble. Of course, the system itself promotes fudging, and his claim to have reduced crime by a third was criticized on that basis. As time passed, CitiStat was adopted by other departments, notably public schools.

In 2007, O'Malley became the governor of Maryland. During his two terms, he followed the best of progressive ideology: tax, spend, repeat.

On his blog he relates a telling story that demonstrates his philosophy and reaction to it. He called a heating company and the woman on the other end asked his name. “O'Malley,” he replied, “like the out-going governor.” “Ah, yes,” she said, “the tax man.”

O'Malley sure did raise taxes: Sales taxes, gas taxes, income taxes, sin taxes (alcohol and tobacco), indirect taxes (minimum wage hikes and public funds for illegal aliens), and so on. During the 2012 gubernatorial election, when O'Malley was term-limited out, Republican candidate Larry Hogan hit Democrats hard using the mantra of O'Malley’s 40 tax hikes. Hogan won the general election.

As The Washington Post reports, O'Malley’s tenure brought a “string of policy changes that will endure long after he departs.” Same-sex marriage, illegal aliens eligible for in-state tuition, higher minimum wage, no more executions, and the kicker: “It’s harder to buy a gun.” In Maryland, that’s saying something.

Education spending reached “record amounts” (though that’s virtually always true even if the increase is small); crime declined impressively (as it did almost everywhere in the U.S.) and the number of people covered by subsidized health care increased dramatically. His supporters say, See? All these were accomplished by, as the Post puts it, “the very tax increases that became so reviled.”

“I’ve done what I think is the right thing to do for the common good of the people I serve,” O'Malley said. Leftists always claim to be doing the practical thing to help people.

On the other side of the ledger, businesses and residents left the state in droves, and Gov. Hogan is left to pick up the pieces.

Whoever Republicans choose to run as the party’s candidate could face some iteration of Martin O'Malley, if not O'Malley himself. He’s smart, he’s ruthless and he already has the media in his pocket – all while Hillary disintegrates. It may end up being a tougher fight for the Democrat nomination than Hillary ever wanted.