With vital decisions nearing, Independent Counsel Kenneth Starr is likely to focus any impeachment report to Congress on evidence in the Monica Lewinsky case rather than other aspects of his Whitewater investigation, an ally close to the prosecutor says.

Final decisions have not been made, but such a report would be expected to focus on perjury and obstruction of justice in the Lewinsky case, where prosecutors have built the strongest and freshest evidence, the Starr ally said, speaking on condition of anonymity.To make such a report under the independent counsel law, Starr must have "substantial and credible" evidence that President Clinton committed a crime. Congress would evaluate such a report to determine whether to begin impeachment proceedings.

Other evidence that doesn't meet that test but was gathered in the four-year probe involving the Clintons' Arkansas real estate venture, Clinton friend Webster Hubbell, the gathering of FBI files and the White House travel office dismissals would be described in a separate report Starr must file with the three-judge appeals court panel that appointed him.

The Starr ally said prosecutors are watching developments with two key witnesses from the earlier aspects of the investigation, Hubbell and Susan McDougal, in case they lead to new cooperation or evidence that could alter current plans.

Key members of Congress have said they have not been told of Starr's plans but expect an impeachment report to be sent soon now that Lewinsky has testified before the grand jury and President Clinton is to give his account Aug. 17.

"I believe we need to get the matter resolved and put behind us," Sen. Arlen Specter, R-Pa., said Sunday on CBS' "Face the Nation." He urged President Clinton not to break his Aug. 17 grand jury date and added: "I hope that Mr. Starr submits his report before the end of August."

Lewinsky told the grand jury that contrary to the president's sworn denial and her own affidavit in January, she had a sexual relationship with Clinton. She also told prosecutors they discussed ways to conceal the relationship, including returning gifts she had received from the president, which might come up in legal proceedings, to his Oval Office secretary, legal sources familiar with her testimony said.

One legal source, speaking on condition of anonymity, said Lewinsky, 25, has been consistent since she first sought immunity from them in January with details of a sexual relationship with Clinton. The source said she told of more than one encounter of oral sex with the president inside the White House. "Her account to prosecutors throughout has been consistent," the source said.