The Associated Press said Thursday night it won’t declare a winner in the race until the results are certified, "given remaining concerns about whether the results as reported by the party are fully accurate."

"AP has reviewed the updated results and will not call a winner, given remaining concerns about whether the results as reported by the party are fully accurate," read an alert from the wire service to its subscribers. "AP will update its tally of the national delegates won in Iowa with that final delegate on Saturday, once the Iowa Democratic Party formally votes to certify the results of the caucuses."

Buttigieg's lead in SDEs narrowly increased after the recount, which changed results in 19 precincts. Sanders is still the popular vote leader, both in caucus-goers' initial preference and the final allocation.

The results announced by the state party, if final, would award 14 national convention delegates to Buttigieg, 12 to Sanders, 8 to Elizabeth Warren, 6 to Joe Biden and 1 to Amy Klobuchar.

But Jeff Weaver, a Sanders campaign senior adviser, told POLITICO that the Vermont senator's team was challenging the numbers. "We have already filed an implementation challenge with the DNC stating that the Iowa Democratic Party conducted its recanvass and recount in a way that violated their delegate selection plan," Weaver said.

Weaver said the campaign's challenge — which was filed with the DNC before the recount results were announced — argued that Buttigieg should not have been able to ask for a recount or recanvass. The Sanders campaign argued that state party's delegate selection plan only allows for a recanvass or recount request if the request would change the allocation of a national delegate. They argued that Buttigieg's recount request did not meet that criteria.

“Even if every precinct submitted for review by the Buttigieg [c]ampaign were changed in Mayor Buttigieg’s favor, it would not have altered the national delegation,” a letter from the Sanders’ campaign lawyers to the co-chairs of the DNC rules and bylaws committee and Iowa state Democratic Party Chair Mark Smith, which was seen by POLITICO, read. “Because [Buttigieg] did not — and could not — make a showing that the national delegation would be altered, Mayor Buttigieg’s request was deficient and should have been denied.”

A DNC spokesperson did not immediately respond to a request for comment.

Buttigieg is, however, declaring victory. "Yet again, these results confirm Pete won the Iowa caucuses," Buttigieg spokesperson Ben Halle said in a statement.

The Iowa results have been marred by controversy since the night of the caucuses. An app that was initially supposed to help ease the reporting process failed, which led to delays in tallying. Following that, results initially reported by the state party contained apparent mathematical and recording errors. A review by The New York Times found that 10 percent of precinct results had some sort of error, but that they appeared unintentional and did not systematically favor Buttigieg or Sanders.

The Nevada caucuses, which took place this past weekend, escaped similar confusion. However, it was not because the caucuses were error-free — a review from The TImes found errors in nine percent of precincts — but because Sanders won Nevada by a significant margin. Similarly, the gap between Biden and Buttigieg for second place was several percentage points, not measured down to decimal places.

Prominent Democrats have called for the end to caucuses, following slow reporting and apparent errors this cycle.

"I believe we should make the process of selecting our nominee even more accessible," former Senate Majority Leader Harry Reid, who was integral in pushing for the Nevada caucuses, said in a statement on Sunday. "That’s why I believe it’s time for the Democratic Party to move to primaries everywhere."

Caucuses have long been criticized as being less democratic than primaries. Caucuses typically draw a much lower turnout than primary contests, due in part to the difficulty of arranging early voting and the time commitment required to participate.