Mark Horan is a senior vice president for Rasky Baerlein Strategic Communications and has worked on numerous Massachusetts political campaigns.

Finally, Republican strategists got what they wanted for Christmas: John Kerry, nominated to be secretary of state. Now the door has swung open for Scott Brown and he can breeze through to give the GOP its first pickup of the 2014 cycle. Or so the theory goes.

Not so fast, everyone.

It’s easy to forget the toxic environment that propelled Brown to his remarkable 2010 victory — and how quickly it has dissipated.

When Brown won the January 2010 special election to fill the Senate seat vacated by the death of Edward M. Kennedy, unemployment in Massachusetts was about 9 percent. Fifty-five percent of registered voters thought the commonwealth was on the wrong track. Ninety percent viewed the recession as far from over (even though economists were already seeing a slight uptick), and 70 percent thought the state’s economy would worsen over the next year.

Protest was in the air. Jeering crowds greeted President Obama when he campaigned in Boston for Brown’s opponent.

The environment was electric, and Brown seized on it. In a debate, he jumped on the moderator’s claim that he was running for “Teddy Kennedy’s seat” with a potent retort: “With all due respect, it’s not the Kennedy seat. It’s not the Democrats’ seat. It’s the people’s seat.”

That line — which Brown adopted for the rest of the campaign — captured the raw anti-establishment sentiment coalescing among Republicans, suburban independents and working-class Democrats, a loose confederation of pocketbook populists ticked off about everything from market crashes to Obamacare to auto bailouts.

But that moment came and went. By the fall of 2010, just nine months after Brown’s victory, Massachusetts voters reelected Gov. Deval Patrick and rejected a tax-cutting ballot by a 14-point margin. This fall, the state gave liberal star Elizabeth Warren an eight-point win over Brown and approved the use of medical marijuana by 26 points. In a sense, Massachusetts regained its blue footing almost as fast as it lost it.

This is not the first time the state has flipped from its traditional blue to red and back to blue. Since Republicans count for less than 12 percent of the state’s registered voters, they need a huge chunk of unaligned voters and maybe a few Democrats to win. With no social issues to fall back on — same-sex marriage has been on the books in Massachusetts since 2004; roughly two-thirds of voters are pro-choice — Massachusetts Republicans seem able to cobble together a majority only in tough economic times.

Thus, Bill Weld became governor when the recession hit in the early 1990s, and Mitt Romney did so after the dot-com bubble burst. But both lost Senate races — Romney to Kennedy in 1994; Weld to Kerry in 1996 — when state unemployment was under 5 percent.

Which brings us back to Brown. The senator struggled throughout 2012 to find his footing in a gentler, more forgiving political environment. The unemployment rate in Massachusetts had dropped to 6 percent as the summer began (and is even lower in Greater Boston), and the mood in the Bay State had turned sunnier: A Suffolk University poll in October found 63 percent of the electorate saying the state was on the right track, a 30-point turnaround from the Brown special election.

If he runs for the seat Kerry is poised to vacate, Brown is likely to face the same problem: how to define himself in a time of relative economic stability and liberal resurgence, punctuated by President Obama’s 23-point win in Massachusetts. By the time Brown lost to Warren last month, his support had dropped significantly among independent women and Democrats.

To be sure, Brown has assets. A poll published this week suggested he is enjoying a sort of post-defeat honeymoon: He is viewed favorably by 58 percent of the electorate. In head-to-head match-ups, he led several congressmen (all of whom lack his statewide recognition) by 17 points or more. Before he leaves the Senate, he may have a chance to raise taxes on the rich, which would enhance his reach-across-the-aisle persona.

But short of the country hurtling over the fiscal cliff and into a recession, Brown won’t have the economic turmoil that fueled his first victory and is often key to Republican success in Massachusetts. As he knows from living in the Bay State all his life, ferocious storms yield an angry, almost black surf. But when the storm goes out to sea, the ocean reverts to its natural color: blue. For the moment, Massachusetts is blue again.