Pete Buttigieg held a narrow lead over US Senator Bernie Sanders onTuesday in the Iowa Democratic Party caucuses. Former vice president Joe Biden was in fourth place, while US Senator Elizabeth Warren was third.

The partial results were released a day after Iowans began the five-month process of picking a challenger to Republican president Donald Trump for November’s election. They were released after confusion over delays in announcing the Monday’s caucus tallies due to a “coding issue” in an app which was used to report the data.

Buttigieg declared a victory: “So, we don’t know all the results, but we know by the time it’s all said and done, Iowa, you have shocked the nation. By all indications, we are going on to New Hampshire victorious”.

The Iowa Democratic Party required that votes be counted on paper, and then tallied electronically. “We have been working day and night to make sure these results are accurate”, state party chairman Troy Price said.

Buttigieg, the 38-year-old former mayor of South Bend, Indiana, had 26.8% of state delegate equivalents. Sanders had 25.2%, Warren was at 18.4% and Biden at 15.5%. Senator Amy Klobuchar was fifth at 12.6%.

“I just don’t understand what that means, at least half of the data. I think they ought to get it together and release all the data”, Warren said. Biden said he was “feeling good” and predicted the results would be close.