By BRIDGET BOWMAN and SIMONE PATHÉ

No matter what he did or how much he tweeted during his first four months in office, President Donald Trump has mostly held on to the loyalty of congressional Republicans — even those who might have the most to lose at the ballot box next year.

But that deference to the White House has begun to erode, slowly and unevenly, over the past week, with one vulnerable Republican congressman even dropping the word “impeachment” on national television.

The events of the past nine days — including the firing of FBI Director James B. Comey, reports that Trump revealed classified information to Russian officials, and reports that Trump asked Comey to stop investigating his former national security adviser’s contacts with the Kremlin — have rocked Capitol Hill.

Some of the pressure on GOP lawmakers to weigh in on an ongoing investigation into possible ties between the Trump campaign and Russian operatives was relieved Wednesday evening when the Justice Department appointed former FBI Director Robert Mueller as a special counsel to oversee the probe.