HARRISBURG — Ranks of lawyers packed the courtroom of Pennsylvania’s state Supreme Court on Friday, with most of them aiming to persuade justices to pick their clients’ preferred map of new congressional districts for the state and reject a Republican-backed map recommended by a lower court judge.

Oral arguments were on course to last for several hours, with the primary election schedule bearing down on high court justices in the presidential battleground state.

Political control in Washington is at stake, as courts and lawmakers in many other states hash out the boundaries of congressional districts to last for a decade, through 2032.

For the most part, Pennsylvania’s Democratic-majority high court spent the morning questioning the competing lawyers before them as to which criteria is the most important for them to use to choose among more than a dozen maps that are all deemed to be constitutional.

One of those debates involved the question of splitting Pittsburgh among two districts, and whether splitting a city should come after splitting a county. Splitting Pittsburgh would create two Democratic-leaning districts, as opposed to drawing one heavily Democratic district with the entire city inside of it and a separate district next door that is politically divided.

Democrats typically propose splitting the city, while Republicans oppose it.

The court court must make the final decision on how to draw the state’s congressional districts after Democratic Gov. Tom Wolf and the Republican-controlled Legislature deadlocked in the once-a-decade exercise of adjusting for demographic shifts.

After three days of testimony, Commonwealth Court Judge Patricia McCullough, a Republican, recommended a map advanced by Republican lawmakers over maps proposed by Wolf, Democratic lawmakers, partisans on both sides and civic-advocacy groups.

In her 222-page report, McCullough gave extra deference to it because it passed the Legislature.

Wolf vetoed it, not a single Democratic lawmaker voted for it and Democrats broadly view it as a partisan map that would tilt the delegation solidly to the GOP.

In their briefs, Republican lawmakers write that McCullough made the correct decision and that they do, indeed, deserve deference.

But briefs by Wolf, Democratic lawmakers, Democratic-leaning voters and good-government groups argue that McCullough made critical errors in applying redistricting principles, expert testimony and legal precedents.

McCullough also lacked any legal basis to favor a plan just because it passed the Legislature, they wrote.

“To adopt the Legislature’s proposed map on this basis would effect a judicial override of the Governor’s veto, in violation of the separation-of-powers doctrine,” wrote one group of voters.

The map sides with Republicans on prominent areas of disagreement between partisans, including whether to split up the city of Pittsburgh and Bucks County, and how to split up the Harrisburg area.

It also sides with Republicans in ensuring that no Republican incumbent is in the same district as another GOP incumbent, despite the fact that the state’s slowest-growing areas are largely represented by Republicans.

Complicating the map-drawing is the fact that Pennsylvania is losing a congressional seat — going from 18 to 17 seats in the U.S. House — because of comparatively slow population growth reflected in the 2020 census.

Pennsylvania’s delegation is currently split evenly, nine Democrats and nine Republicans, and registered Democrats outnumber Republicans by 4 million to 3.4 million.

Democrats say the map picked by McCullough could produce at least 10, and up to 12, Republican-held seats.

A political scientist who testified on the plan for Republicans projected that it had nine Democratic-leaning districts and eight GOP-leaning districts based on statewide election results from 2012-20.

An analysis by FiveThirtyEight, a website that focuses on opinion poll analysis, politics and other topics, projects the map keeps nine Republican-leaning districts, shrinks Democratic-leaning districts from six to five and keeps three toss-up districts.

While it considers the maps, the state Supreme Court has indefinitely postponed the period for candidates to circulate petitions to get on the May 17 primary ballot.

Justices also could delay the primary election.