"I don't know. Whatever the going rate is," Reid said.

He quipped, "Can you figure out how I don't have to pay for it?"

Reid spokesman Jon Summers said the senator had already paid for his ticket "at the full price." Summers declined to say how much the ticket cost.

Ringside seats for the bout are going for $2,000, according to the Web site Gambler's Palace. Other tickets are priced at $1,500, $1,000 and $750. Cheap seats are listed at $350.

Reid was criticized last year when it was disclosed that he accepted free ringside tickets from the Nevada Athletic Commission to three fights between 2003 and 2005 in Las Vegas.

Originally, Reid said he needed to attend the fights to understand boxing regulations and represent Nevada's interests on a pending boxing reform bill.

Reid's office later said that although the senator believed it was "entirely permissible" to accept tickets, he would avoid doing so at future fights.

"I should have understood the difference between something that's legal and ethical and something that just doesn't look right," Reid said in November.

There may be a political motivation for Reid to attend the De La Hoya-Mayweather bout. Reid, who is searching for a candidate to challenge Rep. Jon Porter, R-Nev., in 2008, has said he has tried to persuade De La Hoya to move to Las Vegas.