NetanyahuYonatan Sindel/Flash 90

Prime Minister Netanyahu refused to divulge who he will endorse ahead of the upcoming runoff in the Jerusalem mayoral race.

Moshe Leon will face off with Ofer Berkovitch in two weeks after neither one mustered the 40% support in Tuesday's elections that is required to win outright.

When asked by reporters ahead of his flight to Bulgaria on Thursday, Netanyahu refused to divulge his preference, only saying that "there is already a decision".

"I will support someone who will an excellent prime minister, or rather an excellent mayor of Jerusalem," said Netanyahu. "It is a very important, complex city, I know there are bigger challenges than these. I will make sure to support those who get things done."

Netanyahu had openly supported Jerusalem Affairs Minister Ze'ev Elkin in the race, only to see the heavily favored Likud lawmaker suffer a shock defeat in the first round. Leon, a veteran Likud activist, has been endorsed by some of the Likud's most prominent lawmakers after narrowly beating out Ofer Berkovitch 33% to 29%.

"I've known Moshe for many years and am well aware of his abilities that will undoubtedly help him advance Jerusalem to more achievements as befits our capital," Culture Minister Miri Regev said on Thursday.

Former Interior Minister Gidon Sa'ar, seen by many as Netanyahu's chief rival within the Likud, also endorsed Leon on Thursday. "I call for supporting the national camp's Moshe Leon in the second round of the Jerusalem mayor elections and calling on Likud members to unite around his candidacy," Sa'ar tweeted.