Let’s be real right out of the gate: Sen. Bernie Sanders of Vermont is almost certainly not going to be the Democratic nominee for president in 2016. Hillary Clinton is the most dominant non-incumbent front-runner in modern primary history. It would take a truly special candidate to defeat her, and Sanders, who officially announced he’s running Thursday, is not the politician for the job.

Still, he is the type of candidate who can ensure that liberal interests are well-represented in the Democratic primary — and potentially in Clinton’s campaign platform.

Why doesn’t Sanders have a shot?

Polls show Sanders doesn’t match up well against Clinton. He trails her by nearly 57 percentage points nationally, 54 percentage points in Iowa and 40 percentage points in New Hampshire.

More than that, there seems to be very little desire on the left for a challenger to Clinton. She regularly earns 60 percent support among self-described “liberal” and “very liberal” voters, according to national polls. And Sanders’s colleagues in the Senate with the most liberal voting records — those who would be key to starting a mutiny against Clinton — have already endorsed her.

Sanders is also in a poor position to capitalize on the growing minority vote in Democratic primaries. Not to put too fine a point on it, but he’s an old white guy from Vermont (which is 94 percent white). Remember, Barack Obama was able to win in 2008 because he was able to unite very liberal white voters with black voters who had traditionally backed establishment candidates, such as Walter Mondale in 1984 and Al Gore in 2000, in the face of “fresh” challengers.

Oh, and then there is the little thing of Sanders not actually being a Democrat. He is an independent who caucuses with the Democrats. Sanders has shunned past attempts to be put on the ballot as a Democrat. That won’t keep him from running in the primaries, but don’t be surprised if Clinton brings up the question of party loyalty.

All that said, Sanders likely isn’t jumping into the race to win. He has to know the odds facing him are daunting. He’s in the race to highlight issues he cares about, and he’s in a good position to do that.

First, Sanders is liberal, and can sincerely sell a liberal vision to Democratic primary voters. Unlike Martin O’Malley, whose past public statements qualify as “moderate” according to OnTheIssues.org, Sanders is a “hardcore liberal.” On a standardized scale of -100 to 100 (with -100 being the most conservative and 100 being the most liberal), Sanders hits 54; O’Malley’s only a 25. Clinton is a 53. Sanders also has a very liberal donor base. According to Adam Bonica’s fundraising-based ideological scores (standarized to the same scale as OnTheIssues) Sanders rates with a 78 compared to O’Malley’s 41 and Clinton’s 58. Plus, Sanders had the most liberal voting record of any senator in the last Senate, according to roll call votes.

Moreover, the Democratic field is likely to be a shallow one. With so few serious contenders, Sanders is likely to pass the 15 percent threshold required to win delegates and remain at least somewhat relevant in the early states. Despite the fact that Sanders is fairly unknown, the only poll in Iowa that doesn’t list Joe Biden or Elizabeth Warren as candidates has Sanders at 14 percent. In New Hampshire, Sanders is regularly hitting the low double digits, even with Warren given as a choice. Both Sanders and Warren do best among very liberal voters, so he should pick up at least some of Warren’s hypothetical support (assuming she doesn’t run).

When you fail to reach 15 percent, you risk becoming Dennis Kucinich. You say some things in a debate, and nobody actually cares because you’re not earning any real support. Sanders is in a far better position to be taken seriously and affect the policy discussion.

Sanders’s seriousness as a candidate could shift the dialogue in the Democratic primary. Clinton will have to at least entertain the very liberal wing of her party. There is tentative evidence from the past few primaries that having a liberal challenger ensures a nominee with ideological positions closer to the base:

In the 2004 election cycle, Howard Dean made the Democratic primary almost entirely about the Iraq War. Even though eventual nominee John Kerry voted for the war, he was left taking an anti-war position. According to the National Journal scorecard of key votes, Kerry went from being the ninth-most liberal senator in 2002 to the most liberal in 2003 (i.e. the year leading up to the primary).

In the 2008 cycle, John Edwards shifted the debate on economic stimulus, the minimum wage and a free-trade agreement with South Korea. Then, Obama went from having the 10th-most liberal record on key votes in 2006 per the National Journal to being the most liberal on key votes in 2007.

In the same year, there is also an indication that John McCain moved to the right. While he didn’t cast enough votes to have a National Journal score, his public statements went from likely being too moderate to win the nomination (e.g. where Rick Snyder is today) to being more like those of a mainstream Republican (e.g. like John Kasich is today).

After jostling to be the conservative alternative to McCain in 2008 and fending off a rotating cast of conservative alternatives in the 2012 cycle, by the beginning of 2012 Mitt Romney had moved so far to the right of his statements up to early 2007 that you had to wonder whether he was the same politician.

It’s possible those nominees would have shifted their positions against less ideological opponents. But the point is that primaries can move candidates left or right. Clinton hasn’t been in politics for seven years. She is, as the Washington Post’s Chris Cillizza put it, still developing her campaign platform. Since she last ran for office, the Democratic base has become more liberal. Sanders is the type of candidate who can force Clinton to recognize that reality, even though he has pretty much no shot of winning.