WASHINGTON  A leading Congressional opponent of abortion rights, who is in line to take charge of an influential House panel, plans to press for much stricter limits on the procedure.

The selection of the lawmaker, Representative Joe Pitts, Republican of Pennsylvania, as chairman of the Energy and Commerce Subcommittee on Health presages a major shift on abortion and family planning, according to opponents and supporters of abortion rights.

Opponents of abortion gained about 45 seats in the midterm elections, and they count the next speaker, Representative John A. Boehner, Republican of Ohio, as a staunch ally, virtually guaranteeing more conflicts with the White House on the issue.

Mr. Pitts was chosen last week as the chairman of the subcommittee, which has jurisdiction over private health insurance, Medicaid and much of Medicare, as well as the Food and Drug Administration and the National Institutes of Health.