Washington (CNN) White House Counsel Don McGahn, the former long-haired campaign finance lawyer, has become an effective, if unlikely, leader of a judicial juggernaut destined to be one of President Donald Trump's most enduring legacies.

Federal judges are appointed for life, and McGahn has captained a vetting process that has moved faster than even the renowned judge-picking machine of Ronald Reagan's administration in the 1980s. Trump announced Wednesday morning on Twitter that McGahn will be leaving in the fall after the Senate acts on Supreme Court nominee Brett Kavanaugh

Working closely with conservative advocates and Senate Majority Leader Mitch McConnell, McGahn was crucial to Trump's swift choice of two Supreme Court nominees (Kavanaugh last month and Neil Gorsuch in 2017) and winning Senate confirmation of 26 appeals court judges.

Although the nine-member Supreme Court draws most public attention, the country's 13 appeals courts (the second tier of the three-level US judiciary) can significantly impact the law in American life. The high court takes fewer than 1% of the petitions that reach its doorsteps.

Republican administrations in the last half century have made the restocking of the federal courts a priority -- more than Democrats have -- as they have sought to limit or outright reverse liberal-era precedents, such as those establishing abortion rights, allowing racial affirmative action and limiting religious displays in public places.

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