A Big Law attorney known for battling President Donald Trump's proposed travel bans has joined Gov. Tom Wolf's efforts to defend Pennsylvania's recently re-drawn congressional districts before the U.S. Supreme Court.

Hogan Lovells partner Neal Katyal joined Wolf's legal team last week, and on Monday he filed a response to calls from several Pennsylvania Republican lawmakers to have the U.S. Supreme Court upend a congressional map that the Pennsylvania Supreme Court drew up last month after determining that the previous map was unconstitutionally gerrymandered.

Katyal was acting solicitor general in the administration of former President Barack Obama, and has recently been in the spotlight representing Hawaii in that state's efforts to block the Trump administration from suspending the entry of foreign nationals from several predominantly Muslim countries.

Katyal has agreed to represent the Wolf administration in the redistricting fight pro bono.

Wolf's brief to the U.S. Supreme Court was one of eight filed Monday in Turzai v. League of Women Voters of Pennsylvania. The filings come in response to a request by Republican legislators to have the U.S. Supreme Court stay the newly drawn congressional map while their efforts to have the map vacated work their way through the appellate courts.

In January, the Pennsylvania Supreme Court ruled 5-2 that the state's congressional map drawn up in 2011 had been such a partisan gerrymander that it “clearly, plainly and palpably violate[d] the constitution.” Several weeks later, on a 4-3 vote, the court issued a new map to be used in the upcoming congressional race.

State legislators, led by Speaker of the Pennsylvania House of Representatives Michael Turzai and Senate President Pro Tempore Joseph Scarnati, quickly challenged the new map in federal court, and sought to block its use in the upcoming 2018 election cycle.

After the U.S. District Court for the Middle District of Pennsylvania declined to grant the emergency stay, Turzai and Scarnati filed an application for stay with Supreme Court Justice Samuel Alito, who gave the parties until Monday to respond.

“The Pennsylvania Supreme Court conspicuously seized the redistricting process and prevented any meaningful ability for the legislature to enact a remedial map to ensure a court-drawn map,” the emergency application for stay said.

Jason Torchinsky of Holtzman Vogel Josefiak Torchinsky and Kathleen Gallagher of Cipriani & Werner filed the application Tuesday on behalf of Turzai and Scarnati.

In its response, filed Monday, the League of Women Voters of Pennsylvania, which filed the successful state court challenge to the 2011 map, noted that the Republican legislators had previously asked Alito to stay the Pennsylvania Supreme Court's January decision to toss the 2011 map, and said, “Now it's deja vu all over again.”

“Applicants return to this court, again seeking a stay, raising arguments materially identical to the ones they presented barely a month ago. But their arguments have not improved with age,” said the response, filed by Mimi McKenzie of the Public Interest Law Center and Arnold & Porter's David Gersch. “Their ostensible hook for federal intervention remains an elections clause theory that this court has squarely rejected in decisions dating back nearly a century.”

Wolf, in his response, made similar arguments that the case raised state court issues and that Alito had already rejected similar efforts from Scarnati and Turzai.

“If anything, the current stay request is on weaker ground than the last because the commonwealth has now begun to implement the new map, tilting the equities even further against federal judicial intrusion,” Wolf said in the motion.

In an email, Katyal said, “I'm honored to have joined the team, and very much look forward to the federal courts' evaluation of the thorough and careful opinion of the Pennsylvania Supreme Court. Because the matter is now pending in multiple courts, I won't have further comment at this time.”

Torchinsky and Gallagher did not return a call for comment Monday afternoon.