There's nothing like going to the movies on a rainy day, and in storm-drenched Tampa Republicans have flocked to "2016: Obama's America," a right-wing documentary and surprise box-office hit.

The film provides a dark vision of what would happen if President Barack Obama wins a second term in the November 6 election, which delegates to the Republican National Convention here are determined to prevent.

"In the Georgia delegation they announced the show and the times of the show -- so we decided to come," said Lis Overton. "After the show everybody clapped. The truth was told."

Apparently, others also got the memo.

Sporting their convention t-shirts, caps and even badges, delegates who had come to Tampa to formally crown Mitt Romney as their White House candidate gushed as they left a showing at the AMC theaters in the WestShore Plaza mall.

"We like it. We hope everybody sees it and uses their head and doesn't vote for that man again," Rosalie Tadda, a delegate from Hawaii, told AFP.

Jim Esker, an alternate delegate, agreed.

"I wanted to see another perspective, more than what we are given by the media, so it was quite eye-opening," said Esker, who also hails from Hawaii.

Based on the book "The Roots of Obama's Rage," by conservative author Dinesh D'Souza, the documentary claims the president inherited a left-wing, anti-colonialist world view from his father -- whom he barely knew -- and that if re-elected he would turn to socialism and bankrupt the United States.

"Love him, hate him, you don't know him," reads the poster of the movie, produced in Salt Lake City.

D'Souza, a conservative American commentator of Indian origin who also directs the film, takes viewers over four continents, at times reading phrases from books written by Obama or playing snippets of Obama's voice.

He interviews conservative commentators and experts and plays their remarks over archive footage, in a style reminiscent of liberal filmmaker Michael Moore, who skewered Obama's predecessor George W. Bush.

First released in select cinemas in July, it recently hit screens at more than 1,000 theaters and has brought in steadily larger audiences as the race for the White House has intensified.

This weekend, the film shot to seventh place from a distant 13th, bringing in $6.5 million.

"Documentary film '2016: Obama's America' came out of nowhere to burn up the box office," headlined the daily Washington Post, calling it "the most successful conservative political documentary of all time."

It's precisely for this reason that David Valkema, a delegate from Illinois, went to check it out with a friend.

"It is the biggest documentary in the last 20 years," said the businessman who refers to Obama -- whom he claims to have known during his days as a senator -- as "an empty suit, a fraud."

"I became so angry that we as a nation have elected a man that has no background, that nobody knew anything about," he said. "I want to be part of the process of electing the next man that we all know about."