Since the war started in late February, six Senate Republicans have traveled to Ukraine, as well as one Senate Democrat, 11 House Democrats, and four House Republicans, according to a tally by The Hill.    

"It was [an] emotional experience," the person said of shuttling the lawmakers between meetings with Zelensky in Kyiv and to the suburbs to speak with civilians who survived the Russian occupation.

"When they hear the sirens and see how the people stay ... they understand it's not just through the TV screen, but real, real experience, this is a real, horrible war," the person said.

"It's a big problem if people forget about Ukraine, about this war, this is what [Russian President Vladimir] Putin wants," the person said. "I'm also worried if the people of United States are just tired from the war and forget about it, this is important."