Former Maryland governor Martin O’Malley formally declared over the weekend that he will run for the Democratic presidential nomination. In his speech and a subsequent interview with ABC News, he floated several themes: He has executive experience; the presidency is not a “crown” to be passed back and forth among royal families (i.e., the Clintons and the Bushes); and unlike either Jeb or Hillary, he won’t be beholden to Wall Street.

Martin O’Malley  (Jim Bourg/Reuters)

And O’Malley, 52, is also offering a fourth argument, which seems implicitly designed to draw a contrast with the 67-year-old Clinton: It’s time for a new generation of leaders.

Political historians will recall that another little-known politician who was younger than Clinton also successfully employed this argument against her the last time she ran for president. But it’s worth noting that there are crucial differences between the generational arguments offered by Barack Obama and Martin O’Malley.

BuzzFeed has a good report on his emerging argument, noting that he faces potential pitfalls that worry his supporters:

Friends and former aides said in interviews this week that O’Malley sees his campaign in that historical lens — the unlikely underdog taking on an establishment candidate. Bobby Kennedy against Lyndon B. Johnson in 1968. Hart against Walter Mondale in 1984…

The generational argument, though, has some supporters worried that O’Malley could appear to voters, as several put it, as if he is “playing the age card.”

In Iowa, O’Malley was asked directly whether he is “playing the age card.” He replied:

In Des Moines, surrounded by dozens of “New Leadership” signs stapled to the wall of his state headquarters, O’Malley was asked if he was making age an issue in the campaign.

“No,” he said, “but I do believe that as times change our challenges change. And the things that we were able to do both in Baltimore and in Maryland required new thinking and new perspectives and, yes, new leadership that’s willing to try new approaches.”

In 2008, Obama frequently suggested that a new generation of leaders was required because the older one remained trapped in 1960s culture-war arguments that continued to make national unity elusive, and leaving behind those old arguments was the only way to move the country forward. Clinton, for her part, sometimes hinted, or stated outright, that Obama was naive, for instance when she ridiculed his suggestion that he could magically melt away deep, longstanding ideological divides.

What is the larger point that O’Malley is making in drawing a generational contrast? There’s also cultural dimension to O’Malley’s case, but the emphasis is different. It was perhaps best captured in this quote O’Malley recently gave to journalist James Fallows:

“What I’ve been touched by all around the country is this big generational shift.  This awakening that’s happening especially among people under 40.  I’ve rarely met someone under 40 who wants to blame our nations problems on immigrants, or who denies that climate change is a real threat and that we need to address it.  I don’t meet climate deniers or immigrant haters under 40. So there is fortunately a new generation coming up and we need to speak to the goodness of that generation.”

O’Malley’s implicit argument seems to be that he is better equipped than Clinton to speak to a younger generation of voters who are firmly in favor of more accommodating policies towards undocumented immigrants and gays, and who have concluded that climate change is a real threat that requires a real response. Of course, O’Malley faces an immediate problem: Clinton mostly agrees with him on these issues. She has proposed to build on Obama’s executive actions shielding millions from deportation, and has pledged to defend all of his actions on climate.

And so O’Malley has argued that Clinton has belatedly come around on immigration, declaring support of drivers’ licenses for illegal immigrants after opposing the idea in 2008. As Governor, O’Malley passed a version of the DREAM Act. On climate, O’Malley has come out against the Keystone pipeline; Clinton has not taken a position on it. On gay marriage, O’Malley notes that Clinton evolved on the issue only recently, whereas he helped push through legalization of marriage equality as governor.

As O’Malley has put it, “leadership is about making the right decision…before sometimes it becomes entirely popular.” The basic idea seems to be that O’Malley is more in tune with the cultural priorities of a new generation of Democrats, and less encumbered by the sort of caution that older-line Dems have historically felt about the political risks in embracing them.

But there are obstacles to making this work. For one thing, as Brian Beutler has explained, the political conditions among Dem primary voters are very different this time around, because there was a key focal point for unhappiness with establishment politicians such as Clinton: Her vote for the Iraq War, which was then a huge issue among Democrats. For another, Clinton has already signaled that she is embracing the new generational and cultural priorities rather enthusiastically. And it’s unclear whether rank and file Democrats will care that she has done so belatedly.

Still, O’Malley appears to be giving it a try. It will be interesting to see how far he takes this, given his apparent reluctance to go after Clinton too aggressively. If this at least results in a good debate about how far the Democratic nominee should go in areas like immigration, gay rights, and climate change, so much the better.