WASHINGTON (AP) — The Supreme Court has already heard a major case about political line-drawing that has the potential to reshape American politics. Now, before even deciding that one, the court is taking up another similar case.

The arguments justices will hear Wednesday in the second case, a Republican challenge to a Democratic-leaning congressional district in Maryland, could offer fresh clues to what they are thinking about partisan gerrymandering, an increasingly hot topic before courts.

Decisions in the Maryland case and the earlier one from Wisconsin are expected by late June.

The arguments come nearly six months after the court heard a dispute over Wisconsin legislative districts that Democrats claim were drawn to maximize Republican control in a state that is closely divided between the parties.

The Supreme Court has never thrown out electoral districts on partisan grounds and it's not clear the justices will do so now. But supporters of limits on partisanship in redistricting are encouraged that the justices are considering two cases.

"In taking these two cases, the Supreme Court wants to say something about partisan gerrymandering. It's clear the Supreme Court is not walking away from the issue," said Michael Li, senior counsel at the New York University law school's Brennan Center for Justice.

The justices' involvement in partisan redistricting reflects a period of unusual activity in the courts on this topic. Over the past 16 months, courts struck down political districting plans drawn by Republicans in North Carolina, Pennsylvania and Wisconsin.

Federal judges threw out a state legislative map in Wisconsin and a congressional plan in North Carolina. In Pennsylvania, the state Supreme Court invalidated the state's congressional districts and replaced them with a court-drawn plan.

When the Supreme Court heard Wisconsin's appeal, the court appeared to be split along familiar lines. Four liberal justices seemed inclined to strike down the legislative map and four conservatives appeared more favorable to it. That left Justice Anthony Kennedy seemingly in control of the outcome.

A relatively quick resolution of the case also appeared likely, based on the way the court handled the case. A lower court had earlier struck down the districts and ordered new ones drawn. The justices blocked the drawing of a new map last summer, but set the case for arguments in the first week of its new term in October.

Then in December, the court said it would hear the case about Maryland's 6th congressional district, but provided no further explanation about why it was adding a second redistricting case.

Democrats who controlled redistricting in Maryland in 2011 made a conscious decision to try to increase the party's control of congressional districts from 6-2 to 7-1, said Michael Kimberly, the lawyer representing the Republican challengers.

They took a district that had been centered in rural, Republican-leaning northwestern Maryland, where a longtime Republican incumbent won by 28 percentage points in 2010 and turned it into a district that took in some Democratic Washington, D.C., suburbs and elected a Democrat who won by 21 percentage points in 2012.

The change violated the First Amendment rights of the Republican voters, Kimberly said.

Maryland Attorney General Brian Frosh, a Democrat, said in defending the district that it is competitive for both parties and has elected a moderate Democrat. In 2014, a friendlier year for Republican candidates, Democratic Rep. John Delaney's victory margin dropped to less than 2 points, though it rose again in 2016.

In some ways, the Wisconsin and Maryland cases complement each other. In Wisconsin, the justices have a broad theory about partisan line-drawing. The lower court that ruled for the Democratic challengers concluded that the districting plans were drawn to discriminate against Democrats, the Republicans' advantage would endure even in the face of a strong Democratic showing at the polls and the plans could not be explained by other, non-partisan reasons.

In Maryland, the single-district approach looks a lot like the way civil rights groups try to prove that race played too large a role in the drawing of districts. It would be both a more limited approach than the Wisconsin case, but also feel more familiar to justices who have decided many claims of racial bias in redistricting.

With two cases before them, the justices now have one in which each party is complaining about the other.

That could be significant based on Chief Justice John Roberts' stated distaste for putting the court's credibility at stake in politically charged cases.

"We'll have to decide in every case whether the Democrats win or the Republicans win," Roberts said in the Wisconsin arguments.

Another possibility is that the justices could already have decided that there's a procedural problem in the Wisconsin case, limiting their ability to address the merits of the Democratic voters' claim.

However the court views the two cases, it seems increasingly likely that a decision striking down districts won't result in any changes this year. The court frowns on making these sorts of changes so close to an election. The deadline to get on the primary ballot in Wisconsin is June 1. Maryland's deadline was last month.

The court also has blocked new congressional districts in North Carolina.

Only in Pennsylvania, where the state Supreme Court invoked the state constitution to strike down the congressional map, has a new map been put in place. The Supreme Court refused an emergency request from Pennsylvania Republicans to block it.

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By MARK SHERMAN, Associated Press