HAVANA — A delegation of American lawmakers led by Sen. Patrick Leahy visited Cuba today to gauge the island’s economic changes and stress the importance of freeing a jailed American whose detention has chilled relations between the two countries.

The trip was the first to the Communist-run island by high-level U.S. politicians since President Barack Obama’s re-election in November.

It comes a year after another group of legislators led by Leahy, a Vermont Democrat, came to Cuba and met with President Raul Castro. They also visited Alan Gross, an American jailed since 2009 for illegally distributing communications equipment on the island while on a U.S.-funded democracy-building program.

In their meetings, the lawmakers will stress that freeing Gross, who is serving a 15-year sentence, is a crucial prerequisite for improved ties,.

The lawmakers also hope to get a firsthand look at economic changes on the island instituted by Castro in recent years, including the legalization of limited private enterprise, the creation of a real estate market and the elimination of travel restrictions for most islanders.

The delegation includes Sens. Jeff Flake, R-Arizona; Sherrod Brown, D-Ohio; Debbie Stabenow, D-Michigan; and Sheldon Whitehouse, D-Rhode Island, along with Democratic congressmen Jim McGovern of Massachusetts and Chris Van Hollen of Maryland, Gross’s home state.