The Supreme Court, which effectively ended Mobil Corp.'s takeover bid for Marathon Oil Co. last month, yesterday refused to review lower court rulings that had stymied Mobil in its battle.

The high court, without comment, left intact lower court rulings that the takeover of Marathon, the nation's 16th-largest oil firm, by the nation's second-largest oil company might violate federal antitrust laws. A succession of rulings in lower courts while Mobil was contending against U.S. Steel for Marathon gave U.S. Steel the edge.

After the Supreme Court refused last month to grant an emergency application to block U.S. Steel, the merger between the steel producer and Marathon moved forward. On Jan. 7, U.S. Steel acquired 30 million shares of Marathon--or 51 percent.

The final step in the merger process occurs March 11 when Marathon shareholders vote whether to accept or reject it. Under state law in Ohio, where Marathon has its headquarters, two-thirds of Marathon's shares must be voted in favor of merger for it to happen.

Shareholders whose shares were not acquired by U.S. Steel in the first phase of the merger will receive U.S. Steel 12 1/2 percent notes for their shares if the merger is approved. Some shareholders have gone to court; others say they will vote against the merger because the value of those notes is lower than what they consider a fair price.

U.S. Steel Chairman David M. Roderick said yesterday that the steel company has no intention of changing the terms of its bid.