Another week, another storm of teargas and rubber bullets at a World Cup host city in Brazil. This time, the clashes were in the capital, Brasília, where 15,000 protesters from the Landless Workers Movement marched from the Mané Garrincha football stadium to the Palácio do Planalto state office of the president, Dilma Rousseff.

Riot police using batons and teargas fought off several attempts to invade the building. The demonstrators threw stones and tore down railings which they used as weapons. In the fierce fighting, 12 protesters and 30 police officers were injured.

Rousseff was not in her office at the time, but this latest explosion of unrest is yet another headache for the president in what is supposed to be one of the most triumphant, feelgood years in the nation's history.

Hosting the World Cup was intended to show that Brazil – the land long condemned as the "country of the future – and always will be" – had finally arrived. It seemed a shoo-in for success. The five World Cup wins of the Seleção, the national football team, are arguably the greatest source of national pride among the 200 million population. Sure, given the nation's laidback lifestyle, there were always bound to be a few glitches along the way, but it was taken as a given that the land of carnival and samba would mark the tournament by throwing the best party ever.

Those glib assumptions have taken a battering in the last eight months, starting with the biggest street protest in a generation during last June's Confederations Cup and rising in violent, nerve-jangling intensity to the point where – just four months from kick-off – people are still being killed in protests, workers are dying in the rush to complete unfinished stadiums and the mood of the nation is far closer to unease than alegría – joy.

In the last month, the news has grown worse and the criticism sharper. Five stadiums that were supposed to be ready at the end of December are still under construction, prompting panic among Fifa's executives. Last month, its president, Sepp Blatter, said Brazil was further behind schedule than any host since he joined Fifa in 1975, even though it has had the most time to prepare.

One stadium – the Arena da Baixada in Curitiba – is now in the last-chance saloon. Organisers in the city have two days left to prove they have accelerated the pace of building or the Fifa secretary general, Jérôme Valcke, has warned the venue could be kicked out of the cup. That is almost unthinkable given the logistical nightmare of finding a new venue at this late stage, but the fact that the matter was even raised in public underscores the frustrations the delays have generated.

The dire progress is also at least partly to blame for several deaths. Of the six workers who have been killed in stadium construction accidents, four have lost their lives since late November as the deadline pressure picked up. The latest casualty, Antônio José Pita Martins, was crushed last week in Arena da Amazônia in Manaus, where three people have died preparing the stadium where England will play their opening match against Italy. With no major domestic league teams in the city, the venue is thought unlikely to be filled again for football after July.

The waste of lives and money on such white elephants has added fuel to the anger on the streets. Initially public protests had nothing to do with football. Until last June, most were small, relatively peaceful and focused on single issues such as bus fares, healthcare, evictions and corruption. But Fifa's mega-events have become a lightning rod for these and many other issues. "Não vai ter Copa!" (No World Cup) is now a popular chant at almost every rally.

Violence is a growing problem. Although demonstrations are far smaller than last June, they are often bloodier. The most recent victim was a TV cameraman, Santiago Andrade, who was killed when a protester's flare exploded next to his head during a protest outside the Central do Brasil railway station in Rio de Janeiro.

Police brutality has only added to the problem, both on the streets and in the favelas, where a "pacification" programme aimed at driving out armed gangs has suffered a series of setbacks. Residents' support for the operation has weakened since the torture and murder of a local man, Amarildo de Souza, by police last year.

His home – the Rocinha favela, which sits above the England team's hotel – is now racked by gunfire almost every night. Elsewhere, Comando Vermelho gangsters have assassinated several police officers in what appears to be a resumption of tit-for-tat killings.

Football offers a far from safe refuge. More people die in stadium violence and supporter clashes in Brazil than in any other country. Players are no more immune and only slightly better protected. This was evident in the attack this month on the Corinthians training camp in São Paulo by about 100 angry fans who made a hole in the fence with wirecutters, then assaulted the team. Peruvian striker Paolo Guerrero, who scored the winner against Chelsea in the 2012 Club World Cup final, was throttled. Others had belongings stolen. The players have threatened to go on strike over the lack of safety, which will also be a concern at the World Cup, when Iran will use the same training facility.

For some analysts, such problems highlight the fundamentally disruptive and unhealthy impact of global tournaments, despite the promises of improvements. "What we are seeing in Brazil is an aggravation of ordinary living conditions as cities prepare for the World Cup. Traffic is worse, prices are higher and there has never been any kind of institutional reform to Brazilian football. Violence is a part of daily life in Brazil and to assume that this will go away because people feel good about the World Cup is as irresponsible as it is naive," said Christopher Gaffney, a visiting geography professor at the Fluminense Federal University in Rio de Janeiro. Others, however, dismiss such views as curmudgeonly. Fifa's ambassador, Pelé, insists the tournaments will bring rewards for Brazil – as long as people don't ruin the party mood.

"Now we have three fantastic events: the Confederations Cup, the World Cup and the Olympics. The country can fill up with tourists and receive all the benefits from the tourists. And Brazil's own people are spoiling the party," he said in a recent interview. "I hope that people have good sense: let the World Cup pass on. Then we'll make up for the politicians who are robbing or diverting. This is another thing. Football only brings foreign money and only brings benefits to Brazil."

But King Pelé – as he was known on the pitch – has lost a great deal of respect among the public for an approach that comes across as a blind defence of anything that threatens his many corporate sponsors. Similar appeals last year only brought disdain.

Rousseff has also stepped up the PR drive, according to local media who cite unnamed aides as saying that the president's team plans an advertising campaign to remind people that infrastructure projects have been accelerated by the tournament and are partly funded by private money. The president – who faces elections in October – has declared that the remaining obstacles to the World Cup are simple to overcome. But with huge delays over airport and underground rail projects and suspicions of overly cosy ties between politicians and construction companies, there also appears to be a shift of emphasis away from the hardware and preparations and towards the soft side of the tournament as a great spectacle and a great party. The new mantra – constantly repeated this year by the president and Fifa's Valcke – is that 2014 will be the "Copa das Copas" (Cup of Cups).

It is, of course, not too late for the tournament to be a success. The country remains on an upward, if somewhat wobbly trajectory. Jitters are normal before any big event and every hiccup is magnified by the unusually intense scrutiny of the global media. Past mega-events have all been plagued by negative news – Tibetan protests before the Beijing Olympics in 2008, crime fears before the South African World Cup in 2010, security concerns before the London Games of 2012. Brazil, it is hoped, will also overcome its current hitches once the focus is on what it is good at: football rather than organisation.

But for the moment, there is still a gap between how the event is seen by the politicians in the futuristic but old buildings of Brasília and how it is perceived on the streets. A lot of work needs to be done to unify these two visions and time is not on Brazil's side.

"This is a moment of unrest and uncertainty – both in terms of the cup and also society," the 1970 World Cup winner and social commentator Tostão told the Observer. "The cup will happen. That's certain. There is no way they will let it not happen. But what is success? For the Brazilian people, the cup meant lots of public spending, a lack of lasting infrastructure, a lack of social projects, but for the government a successful cup means something completely different. We're all in doubt right now because we just don't know what's going to happen during the cup."

• This article was amended on Sunday 16 February 2014. In the editing process it was wrongly stated that the Brazilian president was male. This has been corrected.