President Trump is flexing his dominance over the Republican Party to stamp out primaries that would bleed party coffers and fracture the GOP ahead of a treacherous midterm election. Why it matters: Republican operatives say that if the party defies expectations and keeps control of Congress this fall, Trump's ruthless maneuvers to sideline some candidates while forcefully backing others will be a big reason why. By the numbers: Trump has picked favorites in more primaries than any other pres