The week of Donald Trump’s inauguration, Sen. Lindsey Graham (R-S.C.) heard some of the chatter from the new administration about trade tariffs on Mexico, and he made his opposition clear.

“Border security yes, tariffs no,” Graham wrote on Twitter on Jan. 26, 2017. The senator added that Mexico is one of the United States’ largest trading partners and new tariffs could create a “huge barrier” to economic growth.

In a follow-up tweet, the South Carolinian said that tariffs on Mexico would increase the costs for consumers on products imported into the United States, which he said would be “a big-time bad idea.” In an apparent attempt at humor, the GOP senator added at the time, “Mucho Sad.”

Last night, Donald Trump announced his intention to impose new tariffs on Mexico. About an hour later, Lindsey Graham endorsed the policy he’d previously denounced.

“I support President Trump’s decision to impose tariffs on Mexico until they up their game to help us with our border disaster.”

In fairness, it’s worth noting that Graham published a follow-up tweet in which he said he doesn’t “like” tariffs, but the South Carolinian is nevertheless endorsing Trump’s plan.

It comes against a backdrop in which Graham, the chairman of the Senate Judiciary Committee, has advised Donald Trump Jr. on how best to sidestep a congressional subpoena, ignored all kinds of lingering questions about the investigation into the Russia scandal, and admitted he didn’t bother to read Robert Mueller’s report.

Asked specifically last month about evidence of presidential obstruction of justice, Graham said he didn’t care.

Circling back to our earlier coverage, there’s been no shortage of speculation as to what caused Graham’s metamorphosis, and as we recently discussed, there are even occasional conspiracy theories about Trump having something damaging on the senator, which the president uses to extort Graham into compliance.

The truth is simpler.

Regarding U.S. Senator Lindsey Graham, his approval rating among Republicans has continued to rise, it now stands at 74% in the Winthrop Poll. Only 25% of Democrats polled support Graham. “Graham’s approval has benefited from his defense of, and alignment with, President Trump. While Graham’s numbers used to lag those of other Republicans among GOP identifiers, since he has taken up the President’s banner on most every issue, his approval among Republicans in South Carolina has steadily risen,” [Dr. Scott Huffmon, Winthrop poll director] said.

A year ago, Graham’s approval among South Carolina Republicans was 51%, and there was a very real chance the senator would face a primary rival ahead of his 2020 re-election bid.

Today, his approval among South Carolina Republicans is 74% – and the chatter about a primary challenge has disappeared.

There’s no great mystery here. Graham made a simple calculus: constructive legislating imperiled his career, so an overhaul of his tactical position became unavoidable.

The senator recently told the New York Times, “If you don’t want to get re-elected, you’re in the wrong business.”

And it’s the pursuit of this goal that led Graham to shed his skin, transform into a Trump cheerleader, and embrace his role as a fierce partisan. He’s been around long enough to survey the landscape effectively – and in 2019, many Republicans, especially those from ruby-red states, who stray from the White House’s wishes, and fail to swear undying allegiance to Trump, find their careers in peril.

It’s why Graham made a rather dramatic change, and the latest polling suggests his plan is succeeding. Whether he’ll look back at this stage in his professional life, however, and reflect on whether it was worth it, remains to be seen.