A day after being nominated as Republican presidential candidate, Mitt Romney received praise from former President George W Bush, who expressed belief that the former Massachusetts Governor will prove to be a great president.

"Dad (George H W Bush) and I both know what it takes to be President. And there's no doubt in our minds that Mitt Romney will be a great president. He's a good man," the junior Bush said in video message during the ongoing party convention in Tampa, Florida.

"I think Ann Romney will be great. And I think Mitt Romney will do a fabulous job," said Barbara Bush, the former US First Lady as she also appeared in the message along with her daughter-in-law Laura Bush, also the former First Lady.

Recalling old memories, George W Bush told the audience how he and his father revered and treated the White House, the presidency and the Oval Office.

"I remember visiting Dad in the Oval Office when he was president and how much reverence he treated the office. And I tried to do the same thing. I mean, the Oval Office is a place where you make decisions and welcome dignitaries and welcome some friends. But it's a place that always has to be treated with respect and dignity," he said.

"When Dad was President he kindly would invite all of us up to the White House. He actually invited me to the state dinner with the queen. He took a huge risk, a diplomatic gamble but it worked out OK," he said.

The former president also remembered how he was amazed after seeing Russian President Vladimir Putin when the latter had visited the White House.

George's wife Laura lauded her husband for making America see through the difficult times of terror attack with his "determination, toughness and persistence".

On this occasion, George's father and former president H W Bush was also all praise for his son for leading the country with "integrity and honesty".

"There was never a taint of scandal around his presidency. They (Americans) will remember him for being a good, honest President who may be got a lot of things done, but I think the thing I take pride in is integrity," he said.