DENVER | The Colorado Secretary of State’s office announced Monday, April 25, that former state Rep. Jon Keyser’s petition signatures for the Republican U.S. Senate primary were insufficient.

Keyser came up 86 valid signatures short of the 1,500 needed in Congressional District 3, which covers most of western Colorado. Senate candidates seeking to make the primary ballot were required to obtain 1,500 signatures from registered Republican voters in each of the state’s seven congressional districts.

Of the 16,067 signatures Keyser submitted to the Secretary of State’s office, 11,436 signatures were declared valid, according to a press release issued by the Secretary of State spokeswoman Lynn Bartels.

Keyser’s campaign has until the end of the week to formally protest the rejection, according to the press release. Keyser’s communications director Matt Connelly issued a statement shortly after the Secretary of State’s announcement that they will do so.

“We are confident that we secured the necessary number of signatures to appear on the ballot and we will be pursuing legal action to ensure thousands of Coloradans are not disenfranchised,” Connelly said.

Keyser’s apparent ejection from the Senate race leaves four potential candidates: El Paso County Commissioner Darryl Glenn, former Colorado State University athletic director Jack Graham, Colorado Springs businessman Robert Blaha, and former Aurora city councilman Ryan Frazier.

Both Glenn and Graham have already assured themselves a place on the June 28 primary ballot. Graham earned a spot on the ballot after submitting a sufficient number of petition signatures late last month, and Glenn earned his party’s nomination at the Republican state assembly earlier this month.

The Secretary of State’s office is still counting petition signatures for both Frazier and Blaha.

Each of the prospective senators is vying to dethrone incumbent Democratic Sen. Michael Bennet. Bennet won the Colorado Democratic Party’s uncontested nomination at a party assembly earlier this month.