U.S. Democratic presidential candidate Bernie Sanders on Tuesday requested a recount in the close Kentucky presidential primary against front-runner Hillary Clinton, state election officials said on Tuesday.

The recanvass will take place at all 120 county boards of election on Thursday, according to the Kentucky Secretary of State Alison Grimes.

Clinton won Kentucky by just 1,924 votes, according to the unofficial totals posted on the secretary of state's elections page. She won Jefferson County, which includes Louisville and is the largest by far of the state's 120 counties, by nearly 10 times that amount

In his filing on Tuesday, Sanders requested a full check and recount of every voting machine and absentee ballot from all precincts in the counties, according to Grimes' website.

"My office is notifying all county boards of elections that Sen. Sanders has requested a recanvass, and we are reminding them of the laws and procedures to be followed," Grimes said in a statement.

Clinton, a former U.S. senator and secretary of state, narrowly defeated Sanders, a U.S. senator from Vermont, in the May 17 presidential nominating contest in Kentucky, a state she had not been expected to win.

A Sanders campaign representative said the recount request was important for the integrity of the Democratic presidential contest, in which Sanders is continuing to challenge Clinton despite her formidable lead in the number of delegates needed to secure the nomination.

"I think the point is just transparency, it's not just about Kentucky," Sanders aide Larry Cohen said on CNN. "It's about trying to create a context, now and at the (Democratic) convention, that these primaries and caucuses need transparency, they need to be authentic, they need to build confidence among voters, particularly younger voters, that this is not rigged."

Sanders has generally drawn more support from young voters than Clinton.