WASHINGTON – In the week since his acquittal on impeachment charges, a fully emboldened President Donald Trump is demonstrating his determination to assert an iron grip on government, pushing his Justice Department to ease up on a longtime friend while using the levers of presidential powers to exact payback on real and perceived foes. Trump has told confidants in recent days that he felt both vindicated and strengthened by his acquittal in the Senate, believing Republicans have rallied around him in unprecedented fashion while voters were turned off by the political process, according to four White House officials and Republicans close to the West Wing who spoke on the condition of anonymity because they were not authorized to speak publicly about private conversations. Since then, Trump and his aides have moved with haste to clear his administration of those he sees as insufficiently loyal, reaching all the way back to the time of former special counsel Robert Mueller’s probe into Russian interference in the 2016 election. Democrats and outside analysts are raising red flags that Trump is exhibiting a post-impeachment thirst for vengeance that’s gone beyond bending norms and could potentially cause lasting damage to institutions. Some Republican senators, including Tennessee’s Lamar Alexander, Maine’s Susan Collins and Alaska’s Lisa Murkowski, said they found Trump’s effort to pressure Ukraine’s President Volodymyr Zelenskiy inappropriate.