FILE PHOTO: U.S. Senate Majority Leader Mitch McConnell (R-KY) speaks to reporters at the U.S. Capitol in Washington, U.S. March 21, 2017. REUTERS/Jonathan Ernst

WASHINGTON (Reuters) - The U.S. Senate will vote next week on the ratification of Montenegro as the newest member of the NATO alliance, Senate Majority Leader Mitch McConnell said on Thursday, after the Trump administration urged lawmakers to take up the long-delayed matter.

Reuters reported on Tuesday that Secretary of State Rex Tillerson had written to the leaders of the Senate to say Montenegro’s membership in the North Atlantic Treaty Organization was “strongly in the interests of the United States.”

All 28 of NATO’s members must ratify Montenegro’s accession before it can formally join the alliance. The vote in the U.S. Senate was held up for months when at least two Republican senators, Rand Paul and Mike Lee, blocked a quick vote.

The Senate’s Republican leadership had not scheduled a more time-consuming roll call vote until Thursday. McConnell announced in the Senate that there would be a procedural vote on Monday evening, which should clear the way for a final ratification vote later in the week.

Senate aides said they expected the Senate would approve of Montenegro’s NATO membership when the vote takes place.