quote:

The Vermont senator has long brushed off political vulnerabilities and evaded attacks from rivals. But the spotlight on his front-runner status and possible Russian interference could pose challenges.

In the early years, there was his commentary on gender relations featuring a rape fantasy, his support for the Sandinistas and his honeymoon in the Soviet Union.

Once he entered Congress, there were votes to shield gun manufacturers, a commitment to remaining uncommitted to the Democratic Party, and secret plans to mount a 2012 primary challenge against President Obama.

And more recently: the F.B.I. investigation into his family, the heart attack, the resistance to detailing the costs of his signature policy proposal, “Medicare for all.”

Senator Bernie Sanders has the kind of vulnerabilities that make political opponents salivate. Yet throughout his congressional campaigns, the 2016 primaries, and now his second White House bid, one rule has defined the senator’s political rise: Nothing sticks.

Now that durability is about to be tested in ways that Mr. Sanders has never experienced in his 50-year electoral career. The disclosure on Friday that intelligence officials believe Russia has been interfering in the 2020 race to help his candidacy may distract from his campaign message and force him to contend with questions, worries and disinformation about the Russian efforts.

He is also no longer a quixotic junior senator from the idiosyncratic state of Vermont. He is now the Democratic presidential front-runner, and if he captures the nomination, can expect to face a tidal wave of negative advertising. President Trump and the Republican Party would likely spend millions branding him as a socialist.