Judge Brett M. Kavanaugh, the front-runner to replace Justice Anthony M. Kennedy on the Supreme Court, once argued that President Bill Clinton could be impeached for lying to his staff and misleading the public, a broad definition of obstruction of justice that would be damaging if applied to President Trump in the Russia investigation.

Judge Kavanaugh’s arguments — expressed in the report of the independent counsel, Kenneth W. Starr, which he co-wrote nearly 20 years ago — have been cited in recent days by Republicans with reservations about him and have raised concerns among some people close to Mr. Trump. But Judge Kavanaugh has reconsidered some of his views since then, and there is no evidence that they have derailed his candidacy.