DENVER (KDVR) — Unofficial election results as of Thursday afternoon show no candidate reached 50% of the vote in the Denver mayoral race. There will be a runoff to determine a winner between the top two.

Kelly Brough tallied 34,375 votes while 41,926 votes went to Mike Johnston, according to numbers provided by the Denver Office of the Clerk and Recorder.

Candidate Lisa Calderón had 31,164 votes. With approximately 2,400 votes left to be counted, she would be unable to gain enough ground to advance to second place.

Brough, who was former Mayor John Hickenlooper’s chief of staff and the CEO of the Denver Chamber of Commerce, is the first female candidate to make the runoff in Denver’s 164-year history in the mayoral race.

The 171,492 votes counted in the mayoral race still need to be certified or cured.

What it means to “cure” a vote is to clarify any discrepancies or other adjudications from the voter. Additional unofficial results are expected from the clerk’s office at 2 p.m. on Friday.

The runoff for Denver mayor will take place on June 6.