The United States must not allow aid for Ukraine to be held up by political brinksmanship, US Vice President Kamala Harris said on Saturday, as wrangling in Congress blocks US$60 billion worth of military backing.

"As it relates to our support for Ukraine, we must be unwavering and we cannot play political games," she said, next to Ukraine's President Volodymyr Zelenskyy at a press conference.

Expressing confidence in Kyiv's biggest financial and military contributor, Zelenskyy added that he did "not think that our strategic partner will allow itself to stop supporting Ukraine."

The two leaders were addressing the press after holding bilateral talks on the sidelines of the Munich Security Conference.

Harris noted that their last meeting in Munich came two years ago, five days before Russia attacked Ukraine.

"You and I have had many conversations over these past two years and you have shown extraordinary courage – and accomplishment on the battlefield," Harris told Zelenskyy.

"It has been a source of our pride and our commitment to democracy and to democratic principles to support you in every way we possibly can. And our support is unyielding and unending," she underlined.

Thanking Harris for US support since the beginning of the war, Zelenskyy underlined that Ukraine "needs your unity during such a challenging period for us, and of course in the United States."

With the United States in an election year that could send Donald Trump back into the White House, fears have been running high that his return to office could upend the US' current support for Ukraine.

Trump has spoken out against President Joe Biden's military support for Ukraine.

Earlier on Saturday, Zelenskyy said he was ready to take Trump on a tour of the frontlines. (AFP)