WASHINGTON (AP) — The oversight committee chosen by House Speaker Paul Ryan to investigate whether President Donald Trump obstructed an FBI probe has been the most publicly aggressive group involved in the cautious, GOP-led investigations. [...] the fate of its investigation hinges on Ryan's lukewarm support and the sometimes fractious working relationship between its Republican and Democratic leaders. Ryan said Wednesday the House Oversight and Government Reform Committee will take the lead scrutinizing reports that Trump pressed FBI Director James Comey to shut down the bureau's investigation into Trump's former national security adviser, Michael Flynn. Even without resorting to the force of a congressional subpoena, the committee already has turned up key documents and prodded federal agencies into action in the months since Cummings first asked incoming Vice President Mike Pence for information about Flynn's possible conflicts of interest last November, soon after Trump won the presidential election. A series of toughly-worded letters from Chaffetz and Cummings uncovered information in March that Flynn was paid more than $33,000 from RT, the Russian television network branded a propaganda outlet by U.S.