WASHINGTON — For much of the summer, the F.B.I. pursued a widening investigation into a Russian role in the American presidential campaign. Agents scrutinized advisers close to Donald J. Trump, looked for financial connections with Russian financial figures, searched for those involved in hacking the computers of Democrats, and even chased a lead — which they ultimately came to doubt — about a possible secret channel of email communication from the Trump Organization to a Russian bank.

Law enforcement officials say that none of the investigations so far have found any conclusive or direct link between Mr. Trump and the Russian government. And even the hacking into Democratic emails, F.B.I. and intelligence officials now believe, was aimed at disrupting the presidential election rather than electing Mr. Trump.

Hillary Clinton's supporters, angry over what they regard as a lack of scrutiny of Mr. Trump by law enforcement officials, pushed for these investigations. In recent days they have also demanded that James B. Comey, the director of the F.B.I., discuss them publicly, as he did last week when he announced that a new batch of emails possibly connected to Mrs. Clinton had been discovered.

Supporters of Mrs. Clinton have argued that Mr. Trump's evident affinity for Russia's president, Vladimir V. Putin — Mr. Trump has called him a great leader and echoed his policies toward NATO, Ukraine and the war in Syria — and the hacks of leading Democrats like John D. Podesta, the chairman of the Clinton campaign, are clear indications that Russia has taken sides in the presidential race and that voters should know what the F.B.I. has found.