Republican U.S. Rep. Lauren Boebert of Colorado remains locked in an unexpectedly close battle for reelection against Democratic challenger Adam Frisch in the 3rd Congressional District, with Boebert leading by 1,136 votes in unofficial results as of 6:39 p.m. Thursday.

Approximately 5,000 ballots had remained to be counted in Pueblo County around mid-afternoon Thursday, according to figures provided by county elections officials, in what appeared to be the largest batch of outstanding votes in the 27-county 3rd District. Other counties may have smaller numbers of unprocessed ballots, and elections officials can accept ballots mailed from members of military and other overseas voters until Nov. 16.

“Everyone in this district deserves to have their voice heard, regardless of political affiliation, and I am confident that each and every valid ballot will be counted,” Frisch said in a statement Thursday. “In particular, we must honor and respect those who serve our country by ensuring that every military ballot is taken into account. Every vote matters in this incredibly close race and thousands of votes in Pueblo County and from military and overseas voters remain.”

Counties including Pueblo have also begun to publish lists of voters whose ballots were rejected for one of several reasons — often a discrepancy between the voter’s signature on the ballot and the one elections officials have on file. In many cases these voters can “cure” their ballot to ensure that it’s counted, with the Colorado secretary of state’s TXT2Cure program allowing the process to be completed via text message.

In the 2020 general election, 11,085 ballots with signature verification issues were cured via the TXT2Cure program statewide, the secretary of state’s office said Thursday. Another 21,838 signature issues were not cured, and were rejected.

Rejected ballots must be cured by Nov. 16 to be counted. The deadline for county clerks to tabulate a final category of “provisional” ballots — those cast by voters whose eligibility was “not immediately established on Election Day” — is Nov. 18.

With the 3rd District race so close, however, the process of confirming the result could stretch on for weeks.

Colorado law requires an automatic recount, also known as a statutory recount, if the apparent winner is ahead by a number of votes that is equal to or less than 0.5% of their vote total, and Boebert’s current 1,136-vote lead is just over that threshold by several hundred votes. Depending on precisely how many additional votes are counted over the next week, a statutory recount will likely be triggered as long as either Boebert or Frisch appears to have won by fewer than 800 votes.

The secretary of state must order a statutory recount no later than Monday, Dec. 5, and the recount must be completed by Dec. 13.

Losing candidates may also initiate a recount regardless of the winner’s margin, if they pay for the recount themselves. That’s what far-right Mesa County Clerk and Recorder Tina Peters did after losing the GOP primary for secretary of state earlier this year, submitting a $255,000 fee to force Colorado’s first statewide recount in 20 years.

Following the July recount, Peters, a conspiracy theorist who is under indictment for her alleged role in a breach of Mesa County elections systems, gained just 13 net votes and lost by an unchanged 88,579-vote margin. About half of her recount fee was later refunded after final costs were tallied.

A report released this year by Fair Vote, a group that advocates for ranked-choice voting and other election reforms, found that statewide election recounts rarely result in significant shifts.

The surprisingly competitive matchup between Boebert and Frisch has become Colorado’s closest congressional race since 2002, when the newly created 7th District saw a razor-thin contest between Republican Bob Beauprez and Democrat Mike Feeley. In initial results, Beauprez led by 386 votes, but a court-ordered count of provisional ballots reduced that lead to 122 votes.

As required by law, a statutory recount then proceeded, but changed the final outcome by just one net vote, with Beauprez’s election to Congress confirmed by a 121-vote margin.

Frisch said in his statement Thursday that he would continue to make sure all votes are counted but “ultimately respect the results of this election regardless of the outcome.” At her election-night watch party in Grand Junction, Boebert did not answer when asked whether she would do the same.