The senators told reporters that they had "very positive" talks with President Volodymyr Zelenskiy, and that they had visited an energy facility that Coons said had been hit by a Russian strike using an Iranian-supplied drone.
"We can now see that Putin's goal is to get Ukraine afraid by trying to make the winter dark and cold," Coons said in the vast, chilly church that now doubled as a World Food Program aid centre in Kyiv.
The visit comes amid speculation that the Republicans, seen as favourites to take control of the House of Representatives after Tuesday's midterm elections, could dampen U.S. support for Ukraine.
U.S. and other Western military and financial support has been vital to the eastern European nation's fight to repel Russia's invasion.
Top House Republican Kevin McCarthy said in October that American voters would not "write a blank check" to Kyiv during a recession. Portman appeared to be addressing those remarks in Kyiv when he said some of his Republican colleagues had been "misinterpreted."
"It's in America's national security interest that Russia does not succeed (in Ukraine)" Portman said. But he added that there ought to be "more accountability" in the delivery of assistance, without specifying details.
(Reporting by Max Hunder; editing by Tom Balmforth and Bill Berkrot)
