President Alvaro Uribe arrives in Washington this week to continue his campaign to persuade Congress to continue military aid to Colombia, a draft bill for which is announced on Wednesday. But his battle is being undermined by a deepening political crisis at home.
In what has become known as the "para-politics" scandal, growing numbers of ministers and officials have been accused of co-operating with rightwing militias. Recent revelations confirm suspicions long-held by Democrats in Washington of government ties with paramilitaries, strengthening their resolve to cut military aid in the bill to be debated later this month.
The scandal is hurting Mr Uribe's bid to secure a free trade agreement with the US, with politicians being linked to killings of trade unionists by paramilitaries.
However, said Gustavo Petro, the leftist opposition senator who has been most active in denouncing the scandal, concerns that the crisis could cause any immediate damage to Mr Uribe's government are exaggerated.
"The government won't be affected in the short-term, as the Colombian people on the whole don't understand the seriousness of what is happening," said Mr Petro, a former guerrilla of the disbanded M-19 group. He argued that the media have conditioned the public to believe that the leftwing guerrilla group, the Farc, is to blame for most of Colombia's problems, while playing down the paramilitaries' role. The owners of some media groups have been accused of financing the paramilitaries.
Mr Uribe's approval ratings remain at about 75 per cent. "Colombians will not punish Uribe for this, because for the first time their country is safer while the economy has been performing well," says Jorge Londoño, a local Gallup pollster. "They have always known that their politicians are corrupt."
But popularity does not necessarily translate into strong government. "Since his re-election [in 2006] Uribe has been boxed into a corner, he hasn't done anything but defend, defend, defend," says Mr Londoño.
Pedro Medellín, a political scientist in Bogotá, says that Mr Uribe is "besieged" by numerous conflicting interest groups: unruly politicians, jailed paramilitary leaders, the army, business leaders, human rights groups, even the US Congress - leaving little room for manoeuvre. "Uribe's popularity is no use to him at all. It is a weak government with the appearance of being strong," he says.
The "para-politics" crisis could complicate matters further, says Mauricio Romero, an expert on the paramilitaries. He says the peace process, which encourages paramilitaries to confessin return for reduced sentences, is compromised.
"The paramilitaries don't know how much to confess. If they don't tell everything, they risk judges denying them benefits, or even being extradited. If they do tell everything, everyone will end up being guilty - and ultimately no one," Mr Romero says.
If the extent of government involvement with paramilitaries becomes public, "things will get very complicated, and the executive's ability to govern will be seriously weakened", he adds. Paramilitary chiefs say they have had ties with as much as a third of congressmen, almost all pro-government.
But other analysts, such as Alfredo Rangel of the Foundation for Security and Democracy, argue Colombia's institutional strength will enable compromised politicians to be replaced without affecting the day-to-day functioning of government.
Yet many believe that Mr Uribe's greatest threat is the economy, which is showing signs of strain.
Mr Petro says Colombia is in a "narco-bubble", with growth underpinned by a strong inflow of dollars from drug trafficking. This has strengthened the currency - whose 30 per cent appreciation in the last year has damaged exports and employment - and bolstered public spending, triggering a boom in consumer spending.
With productive capacity stretched, that is putting pressure on inflation. Morgan Stanley"To bet that the bubble won't burst before the next elections in 2010 is very risky," says Mr Petro.
Colombia's complex armed conflict originally pitted the government against leftwing guerrillas, including the Revolutionary Armed Forces of Colombia (Farc) and the National Liberation Army (ELN).
Paramilitary groups emerged in the 1980s to counter the guerrillas.
In 2005 most paramilitary fighters were demobilised but while peace talks are under way with the ELN, there is little progress with the Farc.