The head of President Andrzej Duda’s office, Marcin Mastalerek, has been attending the Republican National Convention in Milwaukee, Wisconsin, with another senior presidential aide, Wojciech Kolarski, since Tuesday.

Mastalerek said he believed Vance could be persuaded to support Ukraine, just as he said Duda had helped convince the Republican speaker of Congress, Mike Johnson, to free up a $61-billion aid package for Kyiv.

In April, Mastalerek claimed a lengthy conversation between Johnson and Duda had been instrumental in freeing up the aid, which had been stalled in Congress for months due to party-political disputes.

Mastalerek highlighted the importance of the Polish-American vote in November’s U.S. presidential election, which he said was something the Trump camp was aware of.

He added that another factor that may be persuasive is America’s own economic interests. He said Duda had emphasized that Ukraine is a large and populous country, making it an attractive market with good economic prospects.

“And this perspective works very well on congressmen and senators, who after all have not only defense firms but also tech companies and others in their districts,” Mastalerek said. “I think this is the way to go.”

Trump’s choice of Vance as running mate has been seen as the former president emphasizing his “America first” message. Vance broke with Republican leaders in the Senate to vote against the aid package to Ukraine in April, arguing that the Russian threat to world stability was overstated.

“Vladimir Putin is not Adolf Hitler,” he told the House. “It doesn't mean he’s a good guy, but he has significantly less capability than the German leader did.”

He has also candidly expressed his skepticism over the war since it started.

“I gotta be honest with you, I don’t really care what happens to Ukraine one way or another,” he said in February 2022 shortly after Russia invaded.