A man who threatened Colorado’s secretary of state on Instagram faces two years in prison.

A Nebraska man pleaded guilty on Thursday to threatening Colorado’s secretary of state on Instagram last year, the first conviction resulting from the work of a Justice Department task force focused on combating the intimidation of election officials.

Federal prosecutors said Travis Ford, 42, of Lincoln, Neb., would face up to two years in prison for the social media posts. Secretary of State Jena Griswold, a Democrat with whom Republican allies of former President Donald J. Trump have tussled regarding her overseeing of elections, including the 2020 presidential contest, identified herself as the target.

The task force, created last year in response to a rising number of threats against election officials, has publicly disclosed three criminal cases so far. One of the others involves a Texas man who is accused of sending election-related threats to officials in Georgia; the third centers on a Nevada man who the authorities say made menacing phone calls to an election employee in the Nevada secretary of state’s office. Both of those cases are pending.

The threats against Ms. Griswold began with her wishing her partner a happy anniversary on her personal Instagram account last August. A torrent of insults flooded the replies section, some calling her a traitor and others more ominous in their tone.

Two posts in particular unnerved Ms. Griswold’s office, which reported them to law enforcement officials. The first one referred to George Soros, the billionaire investor and Democratic Party donor whom those on the political right have accused of having an outsize influence over elections.

“Do you feel safe? You shouldn’t. Do you think Soros will/can protect you?”

About ten days later, the same account left another, more menacing comment on the same photo.

“Your security detail is far too thin and incompetent to protect you,” the comment read. “This world is unpredictable these days … anything can happen to anyone.”

Ms. Griswold’s office confirmed the authenticity of the posts, which still appeared on Instagram as of Friday and were cited in court documents from the Justice Department. The posts were removed later in the day by Meta, the social media company that owns Instagram and Facebook, following an inquiry from The New York Times. The company did not immediately comment.

A lawyer for Mr. Ford, who remains free and is scheduled to be sentenced on Oct. 6, did not immediately respond to a request for comment on Friday.

In a statement announcing that Mr. Ford had pleaded guilty, Attorney General Merrick B. Garland said on Thursday that the Justice Department would not tolerate such threats.

“Threats of violence against election officials are dangerous for people’s safety and dangerous for our democracy,” Mr. Garland said.

Ms. Griswold, who is seeking re-election this year as Colorado’s top election official, said that she would never be deterred from doing her job.

“Elections officials across the country have been facing increased threats,” Ms. Griswold said. “It is heartening to see the Department of Justice taking these threats seriously and prosecuting people who make threats against election officials based on the Big Lie.”

Like a host of Democrats in charge of voting, Ms. Griswold has been engaged in a series of legal feuds with Republican election supervisors in several counties.

In May, a Colorado judge sided with Ms. Griswold in a lawsuit against Tina Peters, a pro-Trump election supervisor who is running in the Republican primary for secretary of state. The judge blocked Ms. Peters from overseeing elections this year in Mesa County after she was indicted in March on charges that she tampered with voting equipment after the 2020 election.

Ms. Peters, clinging to conspiracy theories that the election was stolen from Mr. Trump, will appear on the top line of the Republican primary ballot on June 28. She is not the only pro-Trump election official Ms. Griswold has accused of breaching voting equipment in Colorado.

In April, Dallas Schroeder, the Elbert County clerk and recorder, was ordered by a judge to surrender to the secretary of state all external copies of a voting machine hard drive that he had acknowledged making with a scanning device before a software update in August 2021.