CNN

Obama's state director in Nevada died of heart attack Sunday.

(CNN) - Barack Obama said Monday he was "shocked and saddened" to learn of the recent death of one of his top campaign aides in the crucial battleground state of Nevada.

Terrence Tolbert, the Nevada state director of the Obama campaign and a former top aide to New York City Mayor Michael Bloomberg, died of a sudden heart attack in Las Vegas on Sunday. He was 44 years old.

“Terence was a strong force in this campaign, with a positive outlook that brought people together," Obama said in a statement. "He was much loved by his team, who often repeated his motto of 'leave no stone unturned.' His enthusiasm, talent, and warm heart will truly be missed. The thoughts and prayers of the entire Obama-Biden family are with his wife and loved ones."

In a Monday statement, Bloomberg called Tolbert, "one of the most hardworking people in the world."

Tolbert was on a temporary leave from his position as a lobbyist in Albany, New York on behalf of New York City's public schools.