I have, pinned to the side of my desk, a "Murphy for President 2020" button, complete with a smiling picture of Connecticut's junior senator.

The button was sent to me back in March, after I wrote about the speculation bubbling up about a possible Chris Murphy bid for president.

It came with a note from a member of the Democratic State Central Committee, who said she had the buttons made up because she was so excited about the prospects that Murphy might run.

The principal source of that speculation was a news report that Murphy was one of four Democrats that Trump guru Steve Bannon wanted to dig up dirt on, in case he became a Trump challenger.

Indeed, Murphy has surfaced as a reliable and loud Trump critic in Congress, making the regular rounds on cable news shows.

Just this week Murphy made national headlines aggressively attacking Trump on everything from health care legislation to the proposed arms deal with Saudi Arabia.

Murphy got a lot of headlines using the I-word talking about Trump and made some more news headway with his apology to the world just before Trump announced U.S. withdrawal from the Paris climate accord.

So Murphy has in fact been looking like someone posturing for a run for president, with the current president in his sights.

Then I caught an interview with Murphy this week on WNPR, Connecticut public radio, in which he seemed to categorically rule it out.

"Are you interested in running for president?" was the direct question.

"I'm not," was the loud and clear answer.

Murphy went on to talk about the new leadership emerging today in the Democratic Party, which he said is no longer the party of the Obamas and Clintons. He cited some of the rising stars by name, including Sen. Cory Booker and Sen. Kirsten Gillibrand.

"It's a moment when younger leaders in the party can step up," he said.

But he specifically excluded himself as a presidential contender.

"I am interested in having a national voice. I am interested in doing that through the United States Senate," he said in the interview.

"I am interested in being a great U.S. senator from Connecticut ...  I have to get through re-election in 2018," he said.

I am not sure the central committee member who sent me a Murphy button read all the way through the column on Murphy for president speculation.

She seemed to miss my point, anyway — that Murphy wouldn't make for a very good candidate.

He seems to represent blue Connecticut sensibility well, and I think his re-election will be a breeze. Indeed, he plans to use his growing war chest to inspire more political activism in the state.

No credible challenger appears anywhere on the horizon.

But I don't see Murphy as the kind of Democrat who is going to move things beyond, as he notes, what has been the party of the Obamas and Clintons.

Murphy was steadfastly in the Clinton camp for the 2016 election, and I suspect that would not place him well in the 2020 race.

I believe that the new generation of election-winning Democratic leadership is more likely to successfully emerge from somewhere in the Bernie Sanders wing of the party, a train that left the station in the last election without Connecticut's junior senator aboard.

If Steve Bannon is still around to organize Trump political opposition research, he may well exclude Murphy from his next list.

This is the opinion of David Collins.

d.collins@theday.com