The California lawmaker had announced her bid for the White House a year ago
His campaign ad promotes Bloomberg's record as mayor and then promises "to rebuild the country and restore faith in the dream that defines us."
The South Bend mayor has been soaring in polls, but the other candidates let him off easy.
The billionaire media mogul has the money and name recognition to shake up the Democratic presidential race, but he will face huge hurdles to the nomination if he makes the leap to become a formal candidate.
The Liberty and Justice Celebration dinner is the biggest gathering of Iowa Democrats before next year's caucuses.
The company said that it had seen "significant cyber activity" from a group of hackers that it believes "originates from Iran and is linked to the Iranian government."
The author argued that because Buttigieg waited until his early 30s to come out as gay, he would be too preoccupied with sex and drugs to be an effective president.
Democratic White House favourite Joe Biden came under fierce attack for his past record on race in a TV debate.
Analysis: Kamala Harris stood out, Joe Biden had a target on his back, and a few of the candidates were barely there.
25 candidates are standing for the Democrats’ nomination and a further 10 will be heard in a second debate on Thursday night.