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 yesterday’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.

Yesterday, 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 told the Associated Press yesterday. “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.”