WASHINGTON >> The Supreme Court dealt a huge blow to efforts to combat the drawing of electoral districts for partisan gain today in a ruling that could embolden political line-drawing after the 2020 census.

On the court’s final day of decisions before a summer break, the conservative justices ruled that federal courts have no role to play in the dispute over the practice known as partisan gerrymandering. The next round of redistricting will take place in 2021, once census results are available.

In another politically charged case decided today, the court blocked for now the Trump administration’s effort to add a citizenship question to the next census. It’s unclear whether the Trump administration has time to address the court’s concerns. Printing of census forms is supposed to begin next week.

There was no immediate response from the White House on either Supreme Court decision today.

In the redistricting case, voters and elected officials should be the arbiters of what is a political dispute, Chief Justice John Roberts said in his opinion for the court.

The court rejected challenges to Republican-drawn congressional districts in North Carolina and a Democratic district in Maryland.

“Our conclusion does not condone excessive partisan gerrymandering,” Roberts wrote, acknowledging that the North Carolina and Maryland maps are “highly partisan.”

But he said courts are the wrong place to settle these disputes.

In a dissent for the four liberals, Justice Elena Kagan wrote, “For the first time ever, this court refuses to remedy a constitutional violation because it thinks the task beyond judicial capabilities.” Kagan, in mournful tones, read a summary of her dissent in court to emphasize her disagreement.

Federal courts in five states concluded that redistricting plans put in place under one party’s control could go too far and that there were ways to identify and manage excessively partisan districts. Those courts included 15 federal judges appointed by Republican and Democratic presidents reaching back to Jimmy Carter.

But the five Republican-appointed justices decided otherwise.

The decision effectively reverses the outcome of rulings in Maryland, Michigan, North Carolina and Ohio, where courts had ordered new maps drawn, and ends proceedings in Wisconsin, where a retrial was supposed to take place this summer after the Supreme Court last year threw out a decision on procedural grounds.

Critics of partisan manipulation of electoral maps say that when one party controls redistricting, it can exaggerate and entrench its power, even in states that are otherwise closely divided between Republicans and Democrats.

Republicans were the big beneficiaries of the most recent round of redistricting in 2011, following the once-a-decade census, because they scored resounding victories in the 2010 elections.

The court was examining two cases, from Maryland and North Carolina, with strong evidence that elected officials charged with drawing and approving congressional districts acted for maximum partisan advantage. In North Carolina, Republicans ran the process and sought to preserve a 10-3 split in the congressional delegation in favor of the GOP, even as statewide races are usually closely divided. In Maryland, Democrats controlled redistricting and sought to flip one district that had been represented by a Republican for 20 years.

Both plans succeeded, and lower courts concluded that the districts violated the Constitution.

Proponents of limiting partisan gerrymandering still have several routes open to them. Among those are challenges in state courts, including a pending North Carolina lawsuit.