LAS VEGAS — Mitt Romney handily won the Nevada caucuses on Saturday, solidifying his status as the front-runner and increasing his momentum as he seeks to use the month of February to ease doubts within the Republican Party about his candidacy and begin confronting President Obama.

Mr. Romney ran well ahead of his three opponents on a night that delivered his second decisive first-place finish in four days, following his victory in the Florida primary on Tuesday.

He appeared elated as he took the stage at his election headquarters at the Red Rock Casino hotel here, kissing his wife, Ann, who reminded the crowd that Nevada would be important in the general election, and hugging his sons before delivering a speech geared toward the fall.

“This is not the first time you’ve given me your vote of confidence, and this time I’m going to take it to the White House,” he said as the crowd chanted his name. And he delivered a harsh critique of Mr. Obama: “This week he’s been trying to take a bow for 8.3 percent unemployment. Not so fast, Mr. President.”