Loudenvielle-Le Louron, France ? Feeling increasing pressure on the course and off it, Michael Rasmussen has refused to crack and his hold on the Tour de France lead is looking increasingly solid with five days of racing left.

The wiry Dane reeled in repeated breakaway attempts by Alberto Contador, his last major challenger for the yellow jersey, in Monday’s punishing ride along five climbs in the Pyrenees.

One-time race favorite Alexandre Vinokourov won the 15th stage along the Spanish border, his second stage victory this year, continuing a pattern of toggling between a bad showing one day with an exceptional performance the next.

Rasmussen has been a paragon of consistency.

He has needed to be.

The Danish cycling union said last week it had kicked him off the national team because he had missed drug tests before the Tour began. A day later, a former amateur mountain bike racer claimed that Rasmussen had tricked him into carrying a human blood substitute to Italy five years ago.

Monday, the head of cycling’s governing body, the International Cycling Union, joined in with his doubts about Rasmussen.

“With all this speculation around him it would be better if somebody else were to win,” UCI chief Pat McQuaid said Monday. “The last thing this sport needs is more speculation about doping.”

McQuaid added, however, that the Danish rider has “broken no rules, so from that point of view … you have to give him the benefit of the doubt.”

Rasmussen said McQuaid’s opposition was “new to me. I have all the intention to try to win this race.”

Patrice Clerc, the head of Tour organizer Amaury Sports Organization, was quoted in French daily Le Figaro as saying that he “regrets” the Dane’s presence.

“I guess it’s normal … they’re shooting at No. 1,” Rasmussen said, alluding to the intense pressure that seven-time Tour winner Lance Armstrong faced over doping claims. “I’m sure he was under tremendous pressure and under fire for seven years in a row, and still he managed to win the race seven times.”

Customs officials stopped and searched vehicles of Rasmussen’s Rabobank team and those of at least three others – Astana, Discovery Channel and Team CSC – to check for suspicious products. The officials declined to comment.

Many riders want to focus on the race, which is looking more and more like Rasmussen’s to lose with a last big day in the mountains and a pivotal time trial as his main hurdles before the finish Sunday in Paris. Rasmussen said the young Contador was giving him heat up the Peyresourde Pass – the last of five ascents Monday, including the Port de Bales, one of the toughest climbs in cycling.

“He probably has the best acceleration of anybody on the climbs, and I was certainly under pressure, but luckily enough I managed to get back every time,” Rasmussen explained.

Vinokourov broke away near the finish of the 122-mile run from Foix to Loudenvielle-Le Louron, for his fifth career Tour de France stage victory.

It was his second this Tour, after winning Saturday’s time trial.