There is not much Senate Majority Leader Mitch McConnell won't do to score a win for Republicans, no matter how objectionable or unethical. But apparently, even he has his limits — at least when it comes to Donald Trump's temper tantrums.

Senate Majority Leader Mitch McConnell (R-KY) is not shy about flouting Senate rules and traditions to put his party before his country and constitutional obligations.

He was perfectly willing to obstruct President Barack Obama’s Supreme Court nomination for the better part of the year in order to steal the seat for the Republican Party. And when he could not round up enough votes to confirm Donald Trump’s nominee, he did the unthinkable — he nuked the filibuster to ram through then-Judge Neil Gorsuch with a simple majority.

And Trump wants him to do it again, this time by ending the filibuster for legislation so that the Senate can pass Trump’s pipe dream spending bill, with money for his border wall and cuts to critical Obamacare provisions. But with even Republicans objecting to this budget, there simply are not enough votes to grant Trump’s wish.

In another one of his typical Twitter tantrums, Trump encouraged the Senate leader to “change the rules now” or shut down the government. One would think, given McConnell’s record of hyper-partisan game-playing and lack of regard for Senate rules, he would be all too happy to indulge Trump’s demand.

But that’s not happening. On Tuesday, McConnell told reporters he had no intention of nuking the legislative filibuster to push through the Trump’s preferred funding bill.

“There is an overwhelming majority on a bipartisan basis that is not interested in changing the way the Senate operates on the legislative calendar,” he said.

Lack of support has rarely stopped McConnell in the past. A majority of voters, for example — including Republicans — thought GOP leadership was playing petty politics by blocking Obama’s nominee, Merrick Garland, but that did not dissuade McConnell from his obstruction.

The last thing McConnell wants to do, though, is assist Trump with a disastrous and unpopular funding bill for which he would then have to share the blame and even jeopardize his majority in the Senate.

McConnell, after all, represents a state that has benefited greatly from Obamacare, particularly Medicaid expansion. He knows better than to associate himself with an effort to cut funds that help low-income patients cover the cost of health care.

He has been so careful, in fact, that during his 2014 re-election campaign, he outright lied to voters, by telling them that while he wanted to repeal Obamacare, he was committed to protecting the state’s exchange program — which was only possible because of Obamacare.

There is simply no reward for McConnell to go to war with Democrats, and his own party, in order to help the increasingly unpopular president achieve his deeply unpopular legislative agenda.

McConnell might be a cynical, conniving, unethical Senate leader, but he’s not dumb enough to go down with the sinking S.S. Trump. At least, not this round.