Conservative bloggers are leading a campaign to discredit the secretly recorded video of Mitt Romney as the Republican presidential candidate's embattled team mounted a determined fightback.

The bloggers raised questions about a gap in the secret video recording of Romney's speech to a $50,000-a-head dinner in Florida in May and suggested manipulation. The person who made the recording has not been revealed.

David Corn, the reporter on the liberal magazine Mother Jones that posted the video on Monday night, dismissed the attack by the bloggers as a "smokescreen" and "a distraction".

"Everything that I obtained from the source is posted. There is nothing that is not out there. There is nothing that has been edited or deleted," he said.

The source said the video was sent in two segments. "There seemed to be a little gap and I asked the source why. The source said that at the end of the first segment the video timed out or he might have brushed it. He does not know why.

"He turned it back on. He said only one or two minutes elapsed."

One of the main conservatives that raised the the question of the missing minutes, Joel Pollak, of Breitbart.com, wrote that Corn had failed to live up his promise to provide all of the video and "there is new reason to suspect manipulation".

He added: "Mother Jones's entire story now deserves to be treated with suspicion, if not contempt."

Corn said the row over the missing segment is puzzling to him. "What do the conservative critics think might be on this two minutes that might ameliorate what he said earlier?" He added that Romney himself has not challenged the gap.

The row over the missing segment came as Romney's campaign team sought to regain ground by reframing remarks he made in the video that 47% of Americans are government-dependent. Romney and his team placed his comments in the context of a choice for voters between small government and Barack Obama's "culture of dependency".

In a bid to turn the tide of damaging headlines over the video, which captured him dismissing 47% of the electorate as victims who were dependent on government, Romney used a USA Today opinion column to claim his belief in free enterprise contrasted with Obama's redistributive tendencies.

Obama's supporters are equally determined to exploit the 47% row to the full. The Priorities USA Super Pac released a new television ad titled Doors, using clips from the video which was recorded at a $50,000-a-plate fundraiser for Romney at the home of an investment banker in Florida in May.

The Romney team has been on the defensive since the recording's release on Monday. In the video, Romney wrote off the 47% as not being his responsibility.

It is too early for polls to show how much damage the secret video has done to the Romney campaign. It could be next week before the polls settle down and offer a clearer indication of the likely election outcome.

The latest polls give a mixed view of the race, with some suggesting Obama's post-convention lead has largely evaporated while one by NBC and the Wall Street Journal gave him a five-point national lead. Polls in the swing states show Obama opening up a significant lead in Virginia, a state he had been expected to struggle to hold.

The Romney team, in the middle of the candidate's worst week yet, embarked on its fire-fighting effort on Wednesday after a series of frantic conference calls seeking to reassure donors that the campaign remains credible.

Matt Rhoades, Romney's campaign manager, issued a "memo" – in reality, a press release – putting the video in a wider context: the choice facing voters on November 6.

"Mitt Romney's vision for America is an opportunity society, where free people and free enterprise thrive and success is admired and emulated, not attacked. President Obama's vision for America is a government-centered society, where government grows bigger and more active, occupying more of our everyday lives," Rhoades wrote.

A Republican party spokeswoman summed it up as Romney's view that personal responsibility and hard work will deliver recovery against Obama's belief in redistribution and government dependency.

Stephen Hayes, a conservative commentator, lauded the damage-control exercise. "Romney campaign turning into the skid on the video – hitting back hard on size/scope of government. Smart move," he wrote on Twitter, though adding the caveat "Will it last?"

The Romney team has been helped by a decision of the liberal magazine Mother Jones, which started the firestorm by releasing excerpts from the secret video on its website on Monday night, to put out the whole 50-minute video out on Tuesday rather than opt for a drip-feed approach.

In his USA Today op-ed, Romney focused on the small government versus big government theme. "My course for the American economy will encourage private investment and personal freedom. Instead of creating a web of dependency, I will pursue policies that grow our economy and lift Americans out of poverty," he said.

The Romney team is pushing an audio clip from 1998 in which Obama expresses support for redistribution of wealth. Other than on the Drudge Report, which ran the video on Tuesday evening, the clip has failed to gain much traction in the media as it reveals little new about the president's views.

The Obama campaign dismissed the audio clip as a sign of desperation on the part of the Romney campaign.

Obama used an appearance on the Late Show with David Letterman on Tuesday to attack Romney over the video. "One of the things I learned as president is you represent the entire country. If you want to be president, you have to work for everyone."

He added: "All of us make mistakes. … What I think people want to make sure of, though, is you're not writing off a big chunk of the country because the way our democracy works."

RealClearPolitcs, in its average of polls, has Obama at 48% to Romney's 45.4%, suggesting the election is still tight in spite of weeks of gaffes and other setbacks for Romney. An ad blitz by Romney and his supporters and a good performance by the candidate in the first presidential debate with Obama on October 3 in Denver could see the president's lead narrow.

A Gallup poll has Obama only 1% ahead, as does AP, suggesting he has lost almost all of his post-convention poll bounce. An NBC/Wall Street Journal poll has Obama up 5% while Rasmussen puts Romney up 2%.

A Quinnipiac poll on behalf of the New York Times and CBS in six swing states has Obama 1% ahead of Romney in Colorado, 6% in Wisconsin and 4% in Virginia. A poll in the Washington Post gives Obama a staggering 8% lead in Virginia, 52% to 44%.