Senators running for reelection in 1988 are raising far more money in the early stages of the election cycle than they did in their previous races and are far more dependent on campaign contributions from political action committees, according to a study released by Common Cause. The Senate’s champion fund-raiser so far, according to the study, is Lloyd Bentsen (D-Tex.), who has received $5,084,044 since 1983, $3.8 million of it this year. Sen. Pete Wilson (R-Calif.) follows with $4.2 million.