Pennsylvania Governor Tom Wolf addresses the Democratic National Convention in Philadelphia Thomson Reuters By Joseph Ax

(Reuters) - State and national Republican officials will file a federal lawsuit as soon as Wednesday seeking to block a new Pennsylvania congressional map released on Monday by the state's high court, the party's congressional campaign arm said on Tuesday.

The new map would give Democrats better odds of capturing as many as half a dozen U.S. House of Representatives seats in Pennsylvania, where Republicans currently hold 13 of the 18 seats. The Democrats need to flip 24 seats nationally in November's mid-term elections to retake control of the House.

The Pennsylvania Supreme Court drew a new map for the state's 18 congressional districts after previously invalidating the existing lines as an unconstitutional gerrymander, finding that the Republican-controlled legislature drew them to marginalize Democratic voters.

"The suit will highlight the state Supreme Court's rushed decision that created chaos, confusion, and unnecessary expense in the 2018 election cycle," Matt Gorman, a spokesman for the National Republican Congressional Committee, said in a statement.

The court stepped in after lawmakers and Democratic Governor Tom Wolf failed to reach consensus on a new map last week.

Republican U.S. President Donald Trump on Tuesday encouraged Republicans to sue.

"Hope Republicans in the Great State of Pennsylvania challenge the new 'pushed' Congressional Map, all the way to the Supreme Court, if necessary," he wrote on Twitter. "Your Original was correct! Don't let the Dems take elections away from you so that they can raise taxes & waste money!"

Republican leaders in the state legislature said in a statement on Monday that implementing a map "would create a constitutional crisis where the Pennsylvania Supreme Court is usurping the authority of the legislative and executive branches."

Michael Li, a redistricting expert at the Brennan Center for Justice at New York University's law school, pointed out that courts in other states have drawn maps in advance of elections when necessary.

"I think it is the mother of all Hail Marys in terms of its likelihood to succeed for any number of legal and other reasons," he said.

The U.S. Supreme Court rejected an emergency appeal of the Pennsylvania court's initial ruling earlier this month.

(Reporting by Joseph Ax; Editing by Andrea Ricci)