Unfortunately, the number given in the claim is misleading as Bernie Sanders won the Nevada caucus election by much more than 3,444 votes.
According to an article published by Washington Post, for the first time this year, Nevada had early voting. Nearly 75,000 people filled out the ballots. Results from valid ballots had to be integrated with caucus-day counts and Nevada was the third state to vote in the 2020 primary election. The result of the election revealed that Bernie Sanders received 6,788 votes which made him the leading contestant from the Democratic party from Nevada province.
According to statistical data provided by Politico and Associated Press, Bernie Sanders won the Nevada caucus election by obtaining 41,075 votes.