Donald Trump’s joint appearance with Polish President Andrzej Duda in Pennsylvania state has been scrapped, according to a source with knowledge of the Republican presidential candidate’s plans.

Trump and Duda planned to attend the unveiling of a monument at a Polish-American Catholic church in north Philadelphia on Sunday. This would be one of the few times a foreign leader appears alongside a US presidential candidate on the campaign trail.

It is not clear why the meeting was canceled and if they are going to meet at another time, somewhere else.

Voters of eastern European descent have become sought after in the final weeks of the race for the White House between Trump and Vice President Kamala Harris. Pennsylvania is home to fairly large Ukrainian-American and Polish-American communities. As this State is one of the most ambivalent, the votes of these communities could determine the outcome of the election.

Harris says Trump will not oppose Russian President Vladimir Putin’s aggression if he wins the Nov. 5 election, which the former president’s staff has denied.

Many foreign leaders will be in the US in the coming days for the 79th UN General Assembly. Trump told reporters on Wednesday that he would “probably” meet with Ukrainian President Volodymyr Zelensky, and the Ukrainian presidency tonight confirmed the meeting, which will take place next week. Zelensky will deliver a speech on September 25 at the General Assembly in New York, and the next day he will meet with President Joe Biden in Washington and, separately, with Vice President Kamala Harris.