Venezuelan president registers to run for a third term in October with an open-top parade and folk song performance

Venezuelan president Hugo Chávez switched from battling cancer to fighting a re-election campaign on Monday as he formally declared his candidacy in typically ebullient style with an open-top parade through a sea of supporters and a ten minutes singing performance.

Blowing kisses and waving vigorously to the crowd as they chanted political slogans and get-well wishes, the former paratroop commander made his way to the National Electorate Office where he registered for the 7 October elections.

Amid rumours that his cancer is so far advanced that he may not survive until voting day, all eyes were on Chávez's physical well-being but the charismatic leader surprised many of his doubters by walking the short distance from his open-top truck to the registration desk.

If there was any variation from the usual public appearances of the three-time incumbant, it was that he remained closely flanked by aides rather than reaching out to the masses who are at the centre of his socialist programme.

Nonetheless hundreds of thousands of red-shirted supporters, including the flag waving-urban militia, turned out to see him speak. Some chanted "Ooh-Ah! Chávez's isn't going away!" and waved flags.

Chávez has scaled down his usually energetic schedule of rallies and TV appearance in the past year, during which he has undergone surgery on three occasions to remove tumors from his pelvic region.

He spent most of last month in Cuba for radiation treatment. Although his precise diagnosis is treated as a state secret, the president said at the weekend that recent tests showed his treatment was going well.

He was in good voice on Monday, when he followed up on his registration parade with a TV appearance which went for more than two hours and included ten-minutes of singing "joropo" folk-songs and the anthem of the armed forces. He also accused the opposition - which he has nicknamed the "Majunches" (or 'Insipid Ones') - of trying to sell the country's too cheaply to multinationals.

Health concerns do not appear to have dented his popularity. Polls put him ahead of his rival, Henrique Capriles, a 39 year-old lawyer who highlighted his own physical fitness on Sunday by walking and jogging 10km during a large rally of his supporters.

"At many levels, Chávez is battling himself," says Professor Miguel Tinker-Salas, a historian and expert in Venezuela at Pomona College in Los Angeles.

"Many polls, including some from the opposition sectors have him winning the election. The campaign will test whether or not Chávez has overcome the illness that has plagued him for the past year. If he is able to mount an active campaign similar to past years it will be difficult for Capriles to defeat him."

In his appearance on Monday, Chávez belied rumours that he is no longer able to walk due to metastasis. But concerns persist - and not just at street level.

Last week, the veteran US journalist Dan Rather, said a presidential aide had told him Chávez was suffering from metastatic rhabdomyosarcoma, an aggressive cancer that had "entered the end stage" which meant he would only have a couple of months to live.

This was only partially contradicted by Eva Gollinger, a staunch Chávez supporter and editor of the English version of Correo del Orinoco who wrote in response: "Chávez has cancer and he is battling hard against it, with the same strength that he has used to propel a nation forward, and very often, against insurmountable obstacles, but president Chávez is not 'out of the game' as Dan Rather implies morosely".

The firebrand leader - who changed the constitution in 2003 to abolish term limits - is now in a position where his mere existence is enough to confound opponents, but he will have to show stronger signs of recovery to quash questions about his fitness to lead for the next six years.

"There is no doubt that Chávez is the most competitive candidate, and that without him the continuity of his socialist project is at risk, but winning the elections (without a clear diagnosis of his health) only extends the uncertainty the country is living in," says John Magdaleno, a political analyst in Caracas.

"The key mystery is why there is no talk about a Plan B in the government," says Javier Corrales, professor of Political Science at Amherst University.

"That is what's unusual. They are postponing, rather than solving, the possibility of chaos within the leadership."