A Texas lawyer who has advised corporate clients to resist certain workplace inspections by the Occupational Safety and Health Administration faces strong opposition from Senate Democrats as President Reagan's nominee to the three-member panel that hears company appeals of OSHA citations.

A battle over the nomination of Robert E. Rader Jr. to a six-year term on the Occupational Safety and Health Review Commission is expected today at Rader's confirmation hearing before the Senate Labor and Human Resources Committee. Democrats contend there is an anti-OSHA bias in Rader's handling of cases for corporate clients and in his writings.

"A person that has spent a considerable portion of his career trying to keep OSHA from inspecting worksites should not be a part of the review commission," said Sen. Howard M. Metzenbaum (D-Ohio). "If Mr. Rader had his way, he would make it impossible for OSHA inspectors to eliminate job-site hazards, even with a warrant."

Rader, 41, who began serving on the commission last fall as a recess appointee, said yesterday that his record has been distorted by critics who focus on the relatively few cases in which his legal clients contested OSHA's right to inspect their premises.

"I have spent 90 percent of my time advising people how to comply with the OSHA act," he said, adding that in a small number of cases, "I have been opposed to abusive enforcement tactics" by OSHA inspectors. He declined to discuss his record further until his hearing.

Rader's nomination has rekindled a longstanding debate between those who contend OSHA has backed down from aggressive inspections and those who believe enforcement has been heavy-handed. "The Democrats are looking for a place to ambush the administration on this, and they think Rader is it," said a Republican staff member.

Rader, in court cases and in two 1981 articles in the Baylor Law Review, advised employers to deny OSHA inspectors access to facilities unless they had a search warrant. He also said companies should deny access when OSHA obtains a warrant that companies have not had a chance to contest. The Supreme Court ruled in 1978 that if employers object to inspections, OSHA must obtain a warrant by demonstrating probable cause of finding violations.

Several of Rader's clients have been cited for contempt of court for their refusal to allow OSHA access, according to court documents. In a 1982 case, Rader wrote to the Associated General Contractors of Kansas, urging the group to join a court challenge to restrict OSHA's ability to obtain warrants. "I believe the case presents a rare opportunity to establish important constitutional precedent that will significantly restrict OSHA in the future, which will benefit . . . all other employers," he wrote.

In a law review article, Rader said OSHA should not be a "handmaiden" of labor unions and urged employers to assert their rights during OSHA inspections. "Employers should realize that there is very little information that they must furnish OSHA," he wrote.