SIOUX CITY, Iowa — Vermont Senator Bernie Sanders likes to tell a story on the stump about Goldman Sachs, an investment bank that agreed to pay a $5 billion settlement to the US government for pushing suspect mortgage-backed securities in the years before the financial crisis.
And after elaborating on Goldman Sachs as a "corrupt financial institution that has ripped off God knows how many people," he adds a not-too-veiled reference to his challenger, Hillary Clinton.
"Oh, by the way, I forgot to mention, they also provide a lot of campaign contributions and speaking fees to unnamed candidates," he said last week in Iowa.
Sanders maintains that personal attacks on challengers have no place in American politics, and he has applauded Clinton's accomplishments. But he has also been known to criticize her — sometimes just minutes after espousing his clean campaign philosophy.
Sanders may be decrying politics as usual, but he's also picked up tricks of the trade during his 25 years in Washington. (That's two years longer than Clinton.) The white-haired 74-year-old comes across more like a philosophy professor than a modern politician. But the last nine months have shown he has the chops to take on the Democrats' star player, analysts say.
"Bernie Sanders' political skills were deeply underrated in the beginning of this process," said Tad Devine, his longtime campaign adviser. "I think people thought of him as somebody who didn't have the skills to deliver a message on a big stage. ... I think people are just now catching up to the fact that he's very good at this."
That includes the Clinton campaign, which has always said the race in early primary states would be close, but didn't finger Sanders as the likely stalking horse.
Now with just four days before Iowans pick the Democratic nominee, polls show the race is a tossup in the Iowa caucuses and Sanders leading in New Hampshire.
Sanders top campaign aides are weighing whether to rachet up attacks on Clinton's Wall Street record in the finals days of the contest, his campaign confirmed, a move that would further put Sanders more squarely in the conventional politics category. (A Wednesday meeting on that topic was first reported by The New York Times.)
And Sanders's camp might claim cause to take a more aggressive tone — Clinton's operation launched a closing ad Wednesday that, while not mentioning him by name, leaves the impression that Sanders would dismantle the Affordable Care Act and cave to the gun lobby. Sanders's team took umbrage, and sent out a lengthy retort.
"Bernie is incredibly competitive," said Garrison Nelson, a political science professor at the University of Vermont, who has watched Sanders for four decades. "Most socialist politicians in this country wants to lose to show they aren't a part of the system. Bernie does not."
Political trappings that Sanders has long eschewed have slowly been added to his operation. There's the pollster. There's his new habit of rattling off poll numbers at events like a statistician. There's the charter jet, a concept that just months ago he scoffed at.
And there's a super PAC, too — it's run by a nurses union. The group hired a bus, adorned it with Sanders's likeness, and parked nose-to-nose with the candidate's new campaign bus as Sanders spoke in Sioux City.
Signature moments of the campaign have, in retrospect, have come to seem politically clever. When sharing a debate stage with Clinton in October, he declared "The American people are sick and tired of hearing about your damn e-mails!''
That won him points with the Democratic electorate, which likes Clinton. But in subsequent days, he clarified that her e-mails are fair game for others.
On some policies, too, he's been able to thread a needle in way that's almost Clintonesque. Most call them taxes, Sanders's campaign talks about "income-based payments to the government." Since his days as mayor of Burlington, Vt., he has morphed from a self-described "socialist" to "Democratic socialist" to — at times in the last few months — "a Democrat."
On the issue of gun control, a point of weakness for Sanders among activist Democrats, he has attempted a political shift in response to repeated Clinton attacks.
Sanders voted in 2005 to shield gun manufactures from liability from shooting deaths and injury.
He initially explained the vote by pointing to his rural constituents, many of whom own guns. During a forum in Iowa, Sanders was pressed on the vote and insisted it wasn't a "mistake."
Days later, just before a Jan. 17 Democratic debate in Charleston, S.C., Sanders said he would support legislation introduced by Senator Richard Blumenthal of Connecticut that would rescind the broad liability protections he had voted for a decade ago.
But there's a twist: Sanders wouldn't sign on as a cosponsor to the bill unless protections were added for small gun stores, Devine said .
Those who have watched Sanders for years aren't at all surprised by the political skills on display.
Former opponents, too, recall a sharp-edged candidate willing to make expedient moves in the pursuit of victory.
William Meub ran against Sanders in 2002, and tried to push for a robust set of debates. Sanders rebuffed him, agreeing to exchanges only at the end of the election season.
And Sanders has been on message for his entire career, Meub said. "He's very good at trying to tap into what he sees as his base, and playing to his base," he said. "And he's now become a brand."