TAMPA, Florida — Former Massachusetts governor Mitt Romney accepted the Republican presidential nomination with a prime-time pitch to voters on the final night of the party convention in Tampa, Florida.

"Mr Chairman and delegates, I accept your nomination for president of the United States," the 65-year-old Romney said to massive applause after walking in to a standing ovation that lasted several minutes and beginning his speech.

"I do so with humility, deeply moved with the trust you place in me. It's a great honor, it's an even greater responsibility, and tonight I am asking you to walk with me to a better future."

The speech was interrupted briefly by three protesters, two women and one man.

"Democracy is not a business!" one of them chanted. "We need to put people over profits!" Delegates immediately started chanting "USA! USA!" to drown them out.

Security officers rushed over to keep them quiet and there was a struggle for nearly a minute before they appeared to agree to be taken out.

The protesters were rushed outside to a balcony, where security officers interrogated them and then led them away.

One woman identified herself as Rae Abileah, of Code Pink Women for Peace.

"I'm with Code Pink Women for Peace, and we're here to send a message to the Republicans and the Democrats," she told a few reporters.

"It's time to get money out of politics. We need to prioritize people over profits in this country."

Romney's elevation to official challenger to Obama in the November election comes more than five long years after he launched his first White House bid and with the race neck-and neck and dependent on a handful of key states.

His convention address aims to generate campaign momentum on his ensuing 10-week dash across battleground states like Florida, Ohio, Virginia and Colorado, any of which could decide the tight race.

After trailing for months, the multimillionaire former venture capitalist has recently drawn even in national polls with Obama, an incumbent saddled with a sluggish US economy and stubbornly high unemployment.