A US congresswoman who is seeking the Democratic nomination in the 2020 presidential election has hit back after Hillary Clinton appeared to call her “the favourite of the Russians”.

Tulsi Gabbard spoke out after the former US secretary of state Mrs Clinton said she believes the Russians have “got their eye on somebody who’s currently in the Democratic primary and are grooming her to be the third-party candidate”.

Mrs Clinton did not name Ms Gabbard directly, but in a series of tweets, the Hawaiian congresswoman called the 2016 Democratic presidential candidate the “personification of the rot that has sickened the Democratic Party for so long”.

Ms Gabbard also alleged there has been a “concerted campaign” to destroy her reputation since she announced her presidential run in January.

“It’s now clear that this primary is between you and me,” Ms Gabbard tweeted about Mrs Clinton.

“Don’t cowardly hide behind your proxies. Join the race directly.”

There is lingering trepidation in the Democratic Party of a repeat of the 2016 presidential race, when Russia interfered in the US election in an effort to help Donald Trump defeat Mrs Clinton.

US intelligence agencies have warned that Russia also intends to meddle in the 2020 presidential election. Russian president Vladimir Putin has mocked that possibility, joking earlier this month that Moscow would “definitely intervene” again.

Hillary Clinton
Mrs Clinton lost out to Donald Trump in the 2016 election (AP)

During a Democratic presidential debate on Tuesday, Ms Gabbard criticised a TV commentator who she said had called her “an asset of Russia”. She called the comments “completely despicable”.

Without naming Ms Gabbard, Mrs Clinton seemed to echo the commentator’s remark during a podcast appearance this week on Campaign HQ With David Plouffe. Mr Plouffe was campaign manager for former president Barack Obama in 2008 and served as served as a senior adviser to him while he was in office.

“She’s the favourite of the Russians,” Mrs Clinton said, referring to the person she had earlier identified as a woman “who’s currently in the Democratic primary”.

She added: “They have a bunch of sites and bots and other ways of supporting her so far.”

Mrs Clinton also called Mr Trump “Vladimir Putin’s dream” in the interview. She went on to say that Mr Trump’s inauguration speech was “like a declaration of war on half of America”.

Mrs Clinton also described the 2016 Green Party presidential candidate Jill Stein as “a Russian asset”.

The Russians know they cannot win without a third-party candidate, Mrs Clinton added.

Ms Gabbard said on CBSN that she “will not be leaving the Democratic Party. I will not be running as an independent or a third-party candidate”.

Election 2020 Debate
The Hawaiian congresswoman is in the running for the Democratic nomination (AP)

Ms Stein, who ran against Mr Trump and Mrs Clinton as a Green Party candidate, received about 1% of the vote in the 2016 election, but some Democrats said her candidacy siphoned votes away from Mrs Clinton and helped Mr Trump win, particularly in states like Wisconsin.

The senate intelligence committee asked Ms Stein for documents as part of its probe into Russian interference in the election because she attended a 2015 dinner in Moscow sponsored by Russian television network RT with Mr Putin. Ms Stein has said she attended “with a message of Middle East peace, diplomacy and cooperation”.

In a tweet, Ms Stein accused Mrs Clinton of “peddling conspiracy theories to justify her failure instead of reflecting on real reasons Dems lost in 2016”.