Nevada Gov. Brian Sandoval (R) said Friday that he plans to call a September 13 special election to fill the seat Rep. Dean Heller is vacating to join the Senate.

“In anticipation of Congressman Dean Heller’s resignation from the U.S. House of Representatives to serve in the United States Senate, I am preparing to call for a special election,” Sandoval said in a statement. “With an election in early September, Nevada will have a full voice as the House begins its work this fall.”

Heller is expected to be appointed to fill the vacancy created when Sen. John Ensign (R) resigns on Tuesday. Once his House seat becomes vacant, Sandoval will have seven days to set the special election date.

More formal details about how the special election will be carried out are expected to be released by Nevada Secretary of State Ross Miller (D) at 2 p.m. ET on Monday. The law is somewhat unclear about whether the parties have a right to hand-pick their candidates or if the contest will be a free-for-all with an unlimited number of candidates.

Among the candidates expected to run in the special election is former state Assemblywoman Sharron Angle (R), who wrote an email to supporters asking for fundraising help on Friday.