WASHINGTON — The Supreme Court rejected on Monday a second emergency application from Republican lawmakers in Pennsylvania seeking to overturn decisions from that state’s highest court, which had ruled that Pennsylvania’s congressional map had been warped by partisan gerrymandering and then imposed one of its own.

The ruling means a new map drawn by the Pennsylvania Supreme Court will very likely be in effect in this year’s elections, setting the stage for possible gains by Democrats. Under the current map, Republicans hold 12 seats while Democrats hold five and are expected to pick up another when the result of a special election last week is certified.

The latest application was denied by the full Supreme Court without comment or noted dissents.

In a terse ruling in January, the Pennsylvania Supreme Court struck down the state’s congressional map, saying that it “clearly, plainly and palpably” violated the state’s Constitution. The court told state lawmakers to redraw the state’s 18 House districts, which favored Republicans.

Pennsylvania Republicans asked the Supreme Court to block that ruling, but their request was rejected last month by Justice Samuel A. Alito Jr.