HARRISBURG — A Pennsylvania judge Thursday launched a review of competing proposals to redraw the boundaries of the state's congressional districts, the morning after Democratic Gov. Tom Wolf vetoed a plan sent to him by Republican lawmakers.

Commonwealth Court Judge Patricia McCullough warned the parties the hearing could go into the weekend, reflecting the pressure to draw new boundaries for 17 congressional districts in time for the May 17 primary election.

With gridlock in the statehouse, McCullough has to consider at least a dozen different proposed maps that must account for demographic shifts over the past decade in the politically divided state.

Complicating the matter is Pennsylvania's loss of a congressional seat because the state grew more slowly than the rest of the country since 2010, according to U.S. Census findings.

The hearing began with brief arguments from parties backing their own proposals, including Wolf, Democratic and Republican lawmakers and others.

Wolf on Wednesday evening announced he vetoed the plan that passed the Republican-controlled Legislature with every Democratic lawmaker opposing it. In his veto message, he argued that the legislation "fails the test of fundamental fairness."

McCullough, an elected Republican judge, could pick a plan or recommend one, but any decision she makes is highly likely to be appealed to the state Supreme Court, where a 5-2 Democratic majority currently sits.