WASHINGTON (Reuters) - The two Democrats who lead the Iowa caucuses - U.S. Senator Bernie Sanders and former Mayor Pete Buttigieg - both requested a recanvass of some caucus results on Monday, the Iowa Democratic Party said.

A week after the problematic presidential nominating contest, Buttigieg filed a request for a recanvass of 66 precincts and all in-state satellite precincts, while Sanders’ campaign targeted 28 precincts, the party said in a statement.

A total of 143 precincts will be reviewed, removing duplications, it said.

Buttigieg had a slim lead over Sanders in the Feb. 3 nominating contest, which took days to settle after a technical meltdown led to delays in determining the winner.

Candidates had a Monday deadline to request a review. A recanvass involves checking the caucus math worksheets where results were recorded. A recount would be necessary to change the actual numbers on those worksheets, but any review begins with a recanvass, said Iowa State Party Chairman Troy Price.

It was unclear how long the process would take, Price told reporters.

Updated results on Sunday showed Buttigieg with 14 delegates and Sanders with 12. Senator Elizabeth Warren won eight delegates, former Vice President Joe Biden won six and Senator Amy Klobuchar got one.

“While a recanvass is just the first step in the process and we don’t expect it to change the current calculations, it is a necessary part of making sure Iowans can trust the final results of the caucus,” Sanders senior adviser Jeff Weaver said.