Senate Foreign Relations Committee Ben Cardin said he had "deep concerns" over the direction of Hungary's current government. The Democratic lawmaker noted Hungarian Prime Minister Viktor Orban's delay, until today, of European Union assistance for Ukraine, as well as its continuing obstruction of Sweden's NATO membership.

"Partners don't do these things. And I am questioning whether they are a trusted ally for our (visa) waiver program," he told a news conference. The Visa Waiver Program permits citizens from 41 countries to travel to the United States for stays of up to 90 days without a visa.

And Senators Jeanne Shaheen, a Democrat, and Thom Tillis, a Republican, who co-chair the Senate's NATO Observer Group which leads efforts in the chamber in support of the alliance, issued a statement calling on Hungary to change course.

"Hungary's inaction risks irrevocably damaging its relationship with the United States and with NATO," Senators Jeanne Shaheen, a Democrat, and Thom Tillis, a Republican said in a statement.

Sweden, along with Finland, applied to join NATO in 2022 after Russia's invasion of Ukraine. But its membership was held up by Turkey and Hungary, leaving the country in limbo and frustrating NATO allies who see Sweden as an important player in ensuring security in the Baltic region.

Hungary is now the only NATO member that has not approved Sweden's application to join the alliance.

(Reporting by Patricia Zengerle; Editing by Sonali Paul)

By Patricia Zengerle