May told German Chancellor Angela Merkel and European Commission President Jean-Claude Juncker she believed her case that the government - not parliament - should be responsible for triggering Article 50 of the EU's Lisbon Treaty to launch the divorce would win in Britain's highest court, a spokesman said.
May is determined to carry out what she calls "the will of the people" and deliver Brexit. But a High Court ruling on November 3 that parliament must approve the process raised doubts over whether she can trigger Article 50 by the end of March as she planned. It also prompted suggestions of an early election.
Her focus on ensuring the government has the lead on breaking with the EU has incensed some lawmakers, and on November 4, a member of her ruling Conservative Party said he had resigned over "irreconcilable policy differences" with May.
The government will appeal against the ruling in the Supreme Court, which is expected to consider it early next month.
"The focus of the government is on the Supreme Court case, winning that case and proceeding with article 50," May's spokesman told reporters.