Some Democrats are putting up caution signs for Hillary Clinton as she wades back into presidential politics by casting 2020 candidate Tulsi Gabbard as a "Russian asset," mocking President Donald Trump's dealings with a foreign leader and drawing counterattacks from both.

Bernie Sanders, who lost the 2016 nomination to Clinton and is running again in 2020, took to Twitter with implicit criticisms of his erstwhile rival. "People can disagree on issues," Sanders wrote Monday, "but it is outrageous for anyone to suggest that Tulsi is a foreign asset."

Larry Cohen, one of Sanders' top supporters, was more conciliatory but warned in an interview that Clinton could harm the eventual 2020 nominee by weighing in against specific candidates, even a longshot like Gabbard.

The former first lady, U.S. senator and secretary of state has "put a lifetime into the Democratic Party. She deserves to be heard," said Cohen, a prominent member of the Democratic National Committee who also chairs Our Revolution, the spinoff of Sanders' last presidential campaign. But "in this senior leader role she has," Cohen said, "it's her job to embrace the range of politics within the party and not polarize within it."

Her scuffle with Gabbard and other recent headlines she's driven demonstrate that the 71-year-old remains a political lightning rod, just as she's been through much of the last three decades. The dynamics raise questions about how Clinton and her party can best leverage her strengths and navigate her weaknesses through next November.

For her part, aides say Clinton isn't attempting any calculated play.

"The short of it is that she's on a book tour and is feeling unconstrained about speaking her mind," said Clinton spokesman Nick Merrill. "It's easy to over-ascribe a strategy about every word she utters, but it's as simple as that. She's out there telling the truth."

Yet the results can frustrate those trying to win the office that Clinton twice lost, a reality presidential hopeful Cory Booker observed with a carefully calibrated critique while he campaigned Monday in New Hampshire. "We need to focus on winning this election ... talking about the urgencies that we have before us and not indulging in what I think is, for me, not a relevant story," Booker said, targeting the news media more than Clinton or Gabbard.

There's no settled playbook for former nominees — or former presidents — in party politics.

Sitting senators like Democrat John Kerry and Republican John McCain returned quietly to Capitol Hill. Democrat Al Gore became a leading advocate for climate action. McCain's running mate, Sarah Palin, has made perhaps the biggest recent splash as a conservative media sensation who helped stoke a base that ultimately embraced Trump.

But Clinton "is in her own category" as a "global figure," said Karen Finney, a top aide on her 2016 campaign.

The first woman to win a major party presidential nomination — and the national popular vote leader with almost 3 million more votes than Trump — Clinton remains a popular figure in her party, even after enduring criticism for losing key Midwestern states to Trump. For Republicans, she's an evergreen foil, used currently in the Mississippi governor's race, where Democratic nominee Jim Hood, a longtime attorney general, is being attacked for acknowledging he voted for her over Trump.

The 2016 election circumstances, a continued focus on Russian interference in U.S. politics and the ongoing House impeachment inquiry against Trump all add to the intensity of feelings for Democrats and Republicans alike.

"There are people who believe she won — or should have won," Finney said, adding that Clinton's overall resume and the current political dynamics give her "a unique voice and perspective."

The latest fracas started last week when Clinton suggested on a podcast that Russians are "grooming (Gabbard) to be the third-party candidate."

Clinton produced no evidence that Moscow is directly backing Gabbard, but Russian state-owned media and a number of alt-right websites have promoted the congresswoman's Democratic campaign, and the Russian Embassy has defended her on Twitter. A military veteran, Gabbard has carved an unusual political profile with criticisms of long-held U.S. foreign policy and defenses of Trump.

Gabbard retorted by calling Clinton "the queen of warmongers ... and personification of the rot that has sickened the Democratic Party for so long."

Trump piled on as well. "Anybody that is opposed to her is a Russian agent," Trump complained at the White House on Monday. "These people are sick. There's something wrong with them."

Separately, Clinton needled Trump in recent days by tweeting a parody letter in the voice of President John F. Kennedy to Soviet leader Nikita Khrushchev during the Cold War's Cuban Missile Crisis. The document, originally from comedian Jimmy Kimmel's late-night show, played off Trump's recent letter warning the Turkish president that history would judge him "forever as the devil" if he didn't "work out a good deal!" over Kurdish lands in northern Syria.

And amid all that, the State Department released its final report into Clinton's use of a private email server as secretary of state, an issue Trump seized upon in 2016 to paint Clinton as corrupt.

Illustrating the perpetual Clinton dichotomy, most mainstream media and Democratic partisans emphasized the report's core finding that there was "no persuasive evidence of systemic, deliberate mishandling of classified information," while conservative media and Republicans played up the determination that 38 current and former State Department officials violated protocol on handling sensitive information.

Cohen, the Sanders backer, said none of that means Clinton isn't in prime position to help Democrats in 2020. And Booker, even as he lamented the Gabbard kerfuffle, called Clinton an "extraordinary statesperson in our party."

Clinton has headlined at least two DNC fundraisers this cycle and more are expected. Merrill said she talks regularly to several Democratic presidential candidates. And Finney predicts Clinton "will be out on the trail in 2020," if not for the nominee, then for "any of the record number of women who will be running" for other offices.

And while Republicans, including Trump, continue aiming at a long-favored target, not everyone in the GOP thinks it will work as well as it has in the past.

"All the things that she warned us about in 2016 have come true," said GOP strategist Rick Tyler. "So she has the gravitas to weigh in. ... She's now a net positive for Democrats, not a negative."

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