Opinion writer

The Post reports:

Sen. Orrin G. Hatch (R-Utah) will retire from the Senate at the end of this term, he announced Tuesday, a decision that will bring a decades-long congressional career to an end early next year.

“After much prayer and discussion with family and friends, I’ve decided to retire at the end of this term,” Hatch, 83, said in a video posted on Twitter. Hatch is the president pro tempore of the Senate, as well as the chairman of the Senate Finance Committee.

Hatch’s retirement means an open seat race in his Republican-leaning state in this year’s midterm election.

This might be the most consequential Senate retirement ever involving a seat that is highly unlikely to change parties. Here’s what to watch for:

First, the decision represents another Senate setback for President Trump, who wanted to keep Hatch, once a mainstream and practical Republican but more recently an unabashed apologist for Trump, in the Senate. After the announced retirements of Sens. Jeff Flake (R-Ariz.) and Bob Corker (R-Tenn.) as well as the Alabama debacle, Trump may face a far more confrontational Senate, even if the GOP holds onto its majority.

Second, this clears the way for Trump nemesis and former GOP presidential nominee Mitt Romney to run. If elected, Romney would have instantaneous gravitas on a range of issues, including the Russia investigation. It’s no exaggeration to say that he would be the leader of the #NeverTrump Republicans in the Senate and maybe the country. Current GOP senators would, to their chagrin, likely be overshadowed by a new member.

Third, Romney represents a personal and political threat to the president, so Trump and Stephen K. Bannon may well try to persuade another crackpot lackey to run for the seat. That would make for an amusing spectacle, but in Utah, where Trump is less popular (largely due to strong opposition among Mormons) and Romney is beloved, it would likely be another defeat for Team Trump.

Fourth, Romney from the Senate perch may test whether there is a GOP worth defending. If he can organize a center-right opposition to Trump both on policy and character grounds (including financial conflicts), the GOP might still have a pulse, although he could well find himself friendless in a party that has become co-opted by Trump.

Fifth, while Romney is a strong conservative, it is very easy to see him playing deal-maker with Democrats on issues such as infrastructure, trade, job training, and research and development funding. He might even have the nerve to oppose unqualified nominees. In that regard, he can do what Sen. Susan Collins (R-Maine) never managed to do: create a viable center. (Romney, of course, would have an easier time dominating the body if he is the deciding vote, say, in a 50-50 Senate.)

Sixth, we should rethink the math. The conventional wisdom is that Democrats need to pick up a net two seats to win the Senate majority. That would be true even if Romney were elected, but in effect it does not guarantee Trump a majority to support his agenda. To the contrary, Romney would become not unlike Supreme Court Justice Anthony Kennedy, the swing vote who matters most of all in a body divided into opposing ideological camps. On the most consequential matter — Trump’s misconduct and potential impeachment — Romney could well side with Democrats.

Romney has yet to announce that he will run, and it’s always possible that he could lose (although he would be the runaway favorite). However, just two days into the new year, 2018 has already become potentially as exciting and unpredictable as 2017.