As it investigates a suspected kickback scheme in New York’s pension system, the Securities and Exchange Commission has been pushing to bar Steven L. Rattner, a prominent financier and former adviser to the Obama administration on the auto industry, from working in the securities industry for up to three years, according to three people told of the discussions, The New York Times reported.

But Rattner has fiercely resisted the proposed penalty, setting up a face-off with the federal government, according to these people, who spoke on the condition of anonymity because the negotiations are intended to be confidential.

It would be the most severe penalty for any of the Wall Street executives ensnared in the wide-ranging pension investigation, and it would carry a significant stigma for Rattner, whose rise in high finance catapulted him to the top of New York’s social and political hierarchy.

The S.E.C. and the New York attorney general, Andrew M. Cuomo, have suggested that Rattner improperly paid off a political operative to win lucrative business from the New York state pension fund — in one case, by arranging to help distribute a low-budget film for the brother of a pension fund official.

Rattner’s former firm, the Quadrangle Group, paid million in fines to settle with state and federal officials in April, but Rattner was left out of that agreement because he would not accept the S.E.C.’s proposal that he be barred from working on Wall Street, people briefed on the case said.

Now, the S.E.C. must decide whether to pursue separate civil charges against Rattner or drop the case altogether.

The attorney’s general’s office is not involved in the S.E.C. talks: Rattner was granted immunity from criminal action by Cuomo’s office in return for his testimony before a grand jury, said a person briefed on the matter. That deal has complicated Cuomo’s case against Rattner.

But Rattner’s immunity hinges on whether his testimony was accurate. And he could still face civil penalties from the attorney general.

Spokesmen for the attorney general’s office and the S.E.C. declined to comment. A spokesman for Rattner also declined to comment.