MARC THIESSEN: Trump Should Go Nuclear With His Supreme Court Nominee.

In 2013, Democrats broke a nearly four-decade-long precedent and changed Senate rules to eliminate the filibuster for executive branch nominations and appointments to the federal circuit or district courts — allowing them to be confirmed by simple majority. Eliminating the filibuster for political appointments that die with a president’s term was one thing. But Democrats eliminated the filibuster for lifetime appointments to the federal bench as well. Once that line was crossed, Republicans can now rightly ask: Why stop at the district and circuit courts of appeal? If Democrats openly say they will obstruct anyone Trump chooses, why not follow the precedent they set and apply their rules to Supreme Court nominees?

The reason Democrats eliminated the filibuster for judicial appointments was to let Barack Obama stack the federal courts with liberal judges — particularly the U.S. Court of Appeals for the District of Columbia Circuit, the nation’s second-highest court, which reviews many critical cases related to federal laws and regulations. And stack the courts Obama did. He appointed more than one-third of the federal judiciary and reversed the ideological balance of the 13 U.S. circuit courts of appeals. When he took office, 10 circuit courts had conservative majorities. Today, nine have liberal majorities, including the D.C. Circuit.

Going nuclear paid huge dividends for the left. One of the liberal judges Obama put on the D.C. Circuit on a party-line vote was Nina Pillard. She later authored the decision that upheld the Obamacare contraception mandate. . . .

Obama and Senate Democrats used the nuclear option to shift the ideological tilt of the nation’s second-highest court. And if Democrats had controlled the Senate last year, does anyone doubt they would have hesitated to use it to put Merrick Garland on the Supreme Court over Republican objections? Of course they would have. And the next time they are back in the majority, they will not hesitate to use the nuclear option to overcome Republican opposition to a liberal nominee. It is only a matter of time before the nuclear option is invoked. The only question is whether it will be invoked by Republicans now, or by Democrats later.

So why wait?

Why, indeed? Once you’ve shattered traditions for opportunistic gain, they can’t be put back together again. Though, technically, the nuclear button here is in the hands of Mitch McConnell, not President Trump.