(CNN) With the Iowa caucuses now less than a month away, a realization is setting in among the political class: Bernie Sanders has a very credible chance at winning the 2020 Democratic nomination.

Consider:

* A series of polls -- both nationally and in early-voting states like Iowa and New Hampshire -- released over the past month make clear that Sanders and former Vice President Joe Biden are running neck-and-neck.

* Sanders, again, outraised the rest of the Democratic field in the final three months of 2019. He brought in $34.5 million between October 1 and December 21 -- almost $10 million more than former South Bend, Indiana, Mayor Pete Buttigieg, who came in second in the cash dash. ( Biden raised $22.7 million in the quarter.)

* Conservative outlets are beginning to opine about the danger Sanders would represent if elected. "Sanders is not merely an amusing old crank but rather an advocate for truly dangerous ideas that have caused great violence, suffering, and deprivation of freedom throughout the world," the Washington Times wrote in an editorial Tuesday . "Americans may not be clamoring for socialism, but right now, Sanders has a chance of winning a major party's nomination, and in a two-party system, each major party candidate starts off with a decent chance of winning. His emergence should not be dismissed as an idle threat."

* In an interview with CNN's Anderson Cooper on Monday night , Sanders was more pointed in his critique of Biden than he has been in the race to date. Here's exactly what Sanders said:

"I mean, look, Joe and I are friends and I truly like Joe. But what is imperative is that we defeat Trump, the most dangerous president in modern history. And that means you're going to have to have a huge voter turnout. You're going to have to get working people excited. You're going to have to get young people excited.

"Joe Biden voted and helped lead the effort for the war in Iraq, the most dangerous foreign policy blunder in the modern history of this country. Joe Biden voted for the disastrous trade agreements, like NAFTA, and permanent normal trade relations with China, which cost us millions of jobs. You think that's going to play well in Michigan or Wisconsin or Pennsylvania?

"You know, Joe Biden has been on the floor of the Senate, talking about the need to cut Social Security or Medicare or Medicaid. Joe Biden pushed a bankruptcy bill, which has caused enormous financial problems for working families. So, if we're going to beat Trump, we need turnout. And to get turnout, you need energy and excitement. And I just don't think that that kind of record is going to bring forth the energy we need to defeat Trump."

Taken together, the picture is clear: Not only has Sanders lasted longer as a viable candidate than many people thought, but he also will have the resources to fight it out for the nomination for months to come.

And then there's perhaps the most important element of all of this: Sanders appears ready -- in ways he never seemed comfortable with in his 2016 primary challenge to Hillary Clinton -- to draw real contrasts with his fellow Democratic candidates in order to peel votes away from them.

Think back to that 2016 primary. Its defining moment (or one of its defining moments) was when Sanders told Clinton "no one cares about your damn emails" in reference to Clinton's use of a private email server as Secretary of State. That effectively took the issue, which some Democrats even at the time expressed concern about in terms of Clinton's vulnerability in a general election, off the table. And Sanders barely laid a glove on Clinton otherwise -- only offering glancing criticism of her decision to give a series of speeches to corporate America for significant sums. (The Clinton campaign complained that Sanders had been too negative, but there is just very little evidence to back that claim up.)

Sanders in that race seemed generally content to be a cause rather than a campaign. He built a movement for sure. But with the exception of the immediate aftermath of his crushing victory in New Hampshire over Clinton , it never really looked like winning was the main objective.

Interviews like the one Sanders gave to Cooper on Monday night suggest that he won't make that mistake again. (Sidebar: Campaigns -- all campaigns -- are about choices between candidates. Highlighting your strengths is of value, yes. But so too is noting your opponents' weaknesses -- and why they should matter to voters.)

Sanders has clearly read up on Biden's looooong voting record -- supported the invasion of Iraq, backed NAFTA, advocated for a bankruptcy bill -- and is beginning to roll out the clear contrast between the former vice president's record on those issues and his own. (Sanders is helped in all of this because he was in the Senate contemporaneously with Biden and can point to moments where the two differed.) The next question for Sanders will be whether he puts these critiques in television ads in places like Iowa and New Hampshire as the votes in both of those states near.

Whether Sanders continues to take the case to Biden remains to be seen. Ditto whether he will wind up as the Democratic nominee. But what is less ambiguous is that Sanders is in far better position to become the Democratic standard-bearer than most people -- including most Democrats -- expected him to be even as recently as last fall. And the Iowa caucuses are only 27(!!) days away.