CHICAGO (AP) — Illinois’ candidates for U.S. Senate are expressing concern about GOP presidential nominee Donald Trump’s suggestion the United States might abandon its NATO military commitments if he is elected president.

Democratic Congresswoman Tammy Duckworth says in a statement Thursday she believes the U.S. is safer and stronger when it is strengthening diplomatic relationships and “not tearing them down.”

Republican Sen. Mark Kirk says the U.S. “should live up to our obligations.” He added failure to stand by NATO allies like Poland “will only embolden adversaries like Vladimir Putin.”

Trump said in a New York Times interview he would review an ally’s financial contributions before acting under NATO’s mutual defense clause, if the country was attacked by Russia.

Several U.S. administrations have complained many NATO members do not foot their share of alliance costs.