In choosing Brett M. Kavanaugh, 53, to replace Justice Anthony M. Kennedy, President Trump opted for a Washington insider who, according to at least one measure, may be less conservative than Mr. Trump’s first Supreme Court nominee, Neil M. Gorsuch.

According to an analysis based on political donations given before becoming a federal judge, Judge Kavanaugh is estimated to be more conservative than 66 percent of all other current and former federal judges nominated since 1980. Using the same measure, Justice Gorsuch was estimated to be more conservative than 85 percent. About 19 percent of Judge Kavanaugh’s donations went to Richard Cordray, a Democrat who worked with him…