(CNN) —  

The death of Arizona Sen. John McCain has occasioned a number of heartfelt tributes as the nation pays homage to a man who sacrificed much for this country. But how will McCain be remembered in the Senate, the place where he spent the final 30+ years of his life? And how do his legislative accomplishments rank against the list of our greatest senators?

I put those questions – and more – to Ross Baker, professor of political science at Rutgers University and someone who has spent considerable time in the Senate as a senior adviser to both Sens. Patrick J. Leahy (D-Vt.) and Chuck Hagel (R-Neb.).

Our conversation, conducted via email and lightly edited for flow, is below.

Cillizza: Let’s start with a simple word association: When you think of “Sen. John McCain,” what words jump to mind – and why?

Baker: Irascible but lovable. A keen mind and a hot temper. And a junk food addict.

Cillizza: Was the young McCain that came to the Senate in the mid 1980s significantly different from the man we saw in his final decade in the Senate? If so, how?

Baker: The 1980s McCain wanted to be one of the boys, fell in with bad company and spent the next three decades atoning. He spent years living down the Keating Five scandal, even though he got off with a slap on the wrist. In his 2002 memoir, written after his loss to George W. Bush, he was still lamenting that blot on his escutcheon.

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Cillizza: What was McCain’s greatest achievement as a senator? Greatest failure?

Baker: His greatest lasting achievement was his dramatic last-second “no” vote to dismember ACA. His greatest temporary feat was McCain-Feingold [campaign finance reform].

My own high point – though it’s rarely remembered – was his takedown of the Jack Abramoff crew when he was chair of Indian Affairs. He turned Bureau of Indian Affairs and the whole Interior Department upside down. He did major things with a minor committee.

His greatest failure: His persistent support for the Iraq war despite the good bipartisan vibes from the “Three Amigos.” The Keating Savings & Loan scandal of course, though McCain sized up the situation before the others. That scandal tarnished another hero, John Glenn.

Cillizza: If there is a list of the 15 greatest senators ever, is McCain on it? Why or why not?

Baker: He’s not up there with [Henry] Clay, [Daniel] Webster, [John] Calhoun, [Charles] Sumner and LBJ, but he’s a lot closer than Ted Cruz will ever be. Few senators in recent years, however, have had such a stupendous sendoff. He always had the media eating out of his hand. That’s no minor accomplishment.

Cillizza: Finish this sentence: In 50 years, Sen. John McCain will be remembered for ___________.” Now, explain.

Baker: Sad to say but people will probably be puzzled. Re-naming the Russell Senate Office Building for McCain would help, but how many people know who Phil Hart was?

[Cillizza: Baker also shared this story about McCain – and why he was so well-liked in the Senate: “Hagel took a CODEL in 2000, and I found myself seated next to Joe Lieberman on the plane. I asked him who his favorites were among his colleagues, and McCain’s name was the first one out of his mouth. I asked him why and he said to me, ‘Do you know what a mensch is?’ I told him I did. He said ‘You just answered your own question.’”]