Shackled by the internal battle for the GOP nomination, Romney has been closing offices in key battleground states while the president has been firing on all cylinders for months

Barack Obama is quietly accumulating a powerful army of field organisers and volunteers, giving his bid for a second term in the White House a substantial head start over his Republican rivals.

In crucial swing states across America, the Obama re-election campaign, backed by the Democratic party, is already in full battle mode with more than 200 offices open, staff hired and thousands of election events underway.

By contrast, all four Republican candidates – including the increasingly dominant frontrunner Mitt Romney – are so shackled by their internal battle over the party's nomination that they have actually been shutting down operations in critical states at the end of each primary.

In the classic swing state of New Hampshire, Romney closed his only office immediately after the January 10 primary. To the astonishment of local Obama organisers, a "for lease" sign was hung outside the Romney headquarters four days before the vote was held. Obama, by contrast, has seven offices up and running in the state, with more than 25 paid staff.

A 'for lease' sign hangs outside Romney's campaign office in Manchester, New Hampshire, four days before the primary.

A Guardian survey of the activities of the Obama re-election campaign, based on data posted to BarackObama.com, reveals 4,200 election events between now and June. Such an aggressive launch of a presidential election campaign so early in the cycle is unprecedented and threatens to leave the eventual Republican nominee far behind in terms of its grassroots organisation.

At this stage, the emphasis of the Obama campaign is on phone banking and voter registration drives designed to mobilise support, as well as online organising skills and social media training. Though the events are spread across 47 states, they are heavily concentrated in the most critical battleground states that are likely to determine the outcome of the presidential election.

The disparity between Obama's advanced organisation and the relative lack of any equivalent infrastructure on the Republican side devoted to the presidential election in November is stark. It helps explain the rising chorus from conservative leaders calling for a swift end to the party's nomination race and for Rick Santorum, Romney's main contender, to stand aside and let him focus on Obama.

That chorus is likely to grow in volume following Romney's convincing win over Santorum in Wisconsin on Tuesday.

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The problem that Romney faces as the Republican nomination drags on is underlined in Florida. The sunshine state is considered by many political analysts to be the ultimate battleground state, with 29 of the 270 electoral votes needed to win the White House.

Here, the Obama re-election campaign already has 22 offices firing on all cylinders. Some opened as long ago as early 2009, four as recently as last Saturday. Between them, they claim to have put together 6,500 training sessions, planning sessions, house parties and phone banks. Events are being staged across Florida at a rate of up to 30 a day.

Romney until recently had three offices in Florida, all directed to his primary battle against Santorum, Newt Gingrich and Ron Paul. Yet despite the fact that no Republican has won the White House while losing Florida since Calvin Coolidge in 1924, Romney closed all three offices after the January 31 primary.

Calls to the main number of Romney's Florida headquarters are sent to voicemail; the mailbox is full and will not accept further messages.

The headquarters was situated in an office block shaded by palm trees on one side of the Hillsborough River in Tampa. A few hundred yards away on the other side of the river is the Tampa Bay Times Forum where the Republican National Convention is expected to annoint Romney as the party's nominee in August.

Mitt Romney's former headquarters in Tampa, Florida, closed a few days after the primary. Photograph: Ed Pilkington/guardian.co.uk

For prominent Floridian Republicans, the prolonged nomination contest is becoming increasingly frustrating. Art Wood, chairman of the Hillsborough County Republican party that covers Tampa, said that watching the Obama team gather their forces while his side was having to put direct campaigning on hold was "very painful. We had hoped that the nomination would be clinched by now, but that hasn't happened.

"The Democrats are putting together a gigantic organisation through Obama For America. They have millions of dollars at their disposal and are solely focused on getting Obama elected. That's painful to watch as well."

Hillsborough County GOP is only now installing phone lines for phone banking at its party headquarters in Tampa, and the actual work of identifying and contacting prospective voters won't begin until next month at the earliest.

Wood is confident that after the Republican national convention in August, his party's declared nominee will close much of the gap in funding, organising and digital technology and by November will be better placed to take the state than in 2008 when Obama won it by just a 2.8% margin. But he still deeply regrets having to bide his time until then.

The scale of the Obama team's outreach is startling by comparison to the Republicans. Rolling Stone magazine reports that Obama volunteers had already logged one million phone calls to potential supporters as early as last November – fully a year before the presidential election.

The Guardian's review of the Obama re-election campaign, based on a survey of activity logged on BarackObama.com carried out at the end of last month, further illustrates the gulf. Across the country, Obama supporters are gathering in McDonalds fast-food outlets, churches, hair salons, public libraries, farmers markets, living rooms and dining rooms, retirement community centres and even a Missouri funeral parlour.

More than 200 offices are actively campaigning, the majority of which are official Obama For America sites set up directly by the Obama team. About a third of these campaigning offices are run by the Democratic party.

Energy is concentrated in the critical swing states. Florida is top of the events list, with 500 phone banks, voter registration drives and training sessions planned by June, almost half organised by the Obama staff and half by volunteers.

Other battleground states receiving intense attention, judging from events listed on BarackObama.com, include Colorado (287 events planned), Nevada (104), New Hampshire (93), North Carolina (269), Ohio (154), Oregon (344), Pennsylvania (302), Virginia (359) and Wisconsin (220).

Illinois, the president's home state, is also rallying local support early, with some 240 events on its calendar.

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The gulf in the electoral readiness of the two main parties is made more extreme by a digital divide that has opened up. The Obama re-election team, based in Chicago, has invested in a vast digital data operation centred on Facebook and its potential to unleash the political power of friendship.

The strategy revolves around a unified computer database that stores information of millions of committed and potential Obama voters, allowing local organisers to target messages designed to raise money, encourage volunteers and on November 6 get out the vote.

On the Republican side, effort has been put into compiling similar data, but it has been fragmented. Both the prominent conservative strategist Karl Rove and the oil tycoons the Koch brothers have been putting together their own voter databases, but there is understood to be no communication between the lists, thus limiting their potency.

Mitt Romney has also been generating his own voter list, but it is nowhere near as comprehensive as Obama's.

The big question is whether the technical prowess of the Obama campaign this year can overcome the inevitable waning of voter passion and enthusiasm that flows from a bid for a second term. Obama's first presidential election in 2008 unleashed exceptional levels of devotion from supporters across the country, and though his senior staff claim they are already witnessing similar levels of enthusiasm this year, few independent observers expect such a spectacle to be repeated.

It remains to be seen whether the Obama campaign can hustle its vast grassroots network into action and translate that into eventual votes. The Guardian's survey of all events on BarackObama.com revealed little to no obvious activity in 20 states, though they tend to be the less electorally sensitive ones where the outcome of the election is in less doubt.

About a third of all upcoming events in the campaign's website are organised by the campaign offices, suggesting that the Obama re-election team and Democratic Party remain strong top-down drivers of volunteer activity. There are exceptions in battleground states like Pennsylvania and Arizona, where the grassroots boasts far more events than both the Obama campaign and Democratic Party combined.

In 2008 the Obama campaign galvanised the youth vote as never seen before, but a close review of events on BarackObama.com also shows relatively few on campuses or oriented toward students.

In Florida, too, the Obama team says it is focusing on the youth vote, a reflection of the importance of that demographic in 2008 when 15% of those who voted in Florida were under 30. Obama commanded 61% of their ballots to John McCain's 37%.

A training session for Obama campaign staff on how to use social media for election purposes in St Petersburg, Florida. Photograph: Ed Pilkington/guardian.co.uk

At a digital training event in St Petersburg, Florida, about 30 people gathered to hear a key Obama staffer talk about the importance of Facebook and Twitter in this year's contest. One of the attendees was Merida Lloyd, aged 23, a graduate student at the University of South Florida.

She was invited by the Obama campaign in January to become one of their "spring fellows" – a volunteer organiser – and now spends about 15 hours a week canvassing for the president on campus.

Lloyd has set up a university Facebook page and has access to the central Obama database from which she draws the details of potential supporters in the 18 to 24 age range. "The most effective way to reach people is to go to them," she says. "So I go to the bars where they hang out and talk to people of my own age group."

Aubrey Jewett, a political scientist at the University of Central Florida, said that in a close race in Florida, Obama's superiority in on-the-ground organising could prove decisive. "The bottom line for Obama is that he has to match the mobilisation he achieved in 2008 among minority and young voters. One of the best ways to do that is to have direct voter contact – that's more effective than spending millions advertising on television."

But John Geer of Vanderbilt University, who has studied the impact of negative TV advertising, said it was not a matter of either/or. "Obama has a phenomenal organisational strategy, but he will also be incredibly well funded to have heavy TV advertising."

Geer added that Romney still had time to play catchup. "You can get a field operation up and close the gap pretty quickly. There's a lot of uncertainty among voters out there, and in the end this election will be determined by the state of the economy and whether Obama can make a case for having four more years."