Supreme Court Chief Justice John Roberts is not facing Senate confirmation this week, but one couldn't help but think he was being reviewed based on the first day of Sonia Sotomayor's confirmation hearing.

Roberts, like all federal judges has lifetime tenure and will never need approval from the Senate again, but that hasn't stopped Senate Judiciary Committee Democrats from repeatedly going after the Roberts' notable line from his 2005 confirmation hearing about a judge being no more than an umpire who impartially calls balls and strikes. 

"Umpires don't make the rules; they apply them. The role of an umpire and a judge is critical," Roberts said in his opening statement at the time. "They make sure everybody plays by the rules. But it is a limited role. Nobody ever went to a ball game to see the umpire.

"And I will decide every case based on the record, according to the rule of law, without fear or favor, to the best of my ability. And I will remember that it's my job to call balls and strikes and not to pitch or bat," Roberts said.

Four years later, that comparison still rankles Democrats who see Roberts as anything but impartial. At least five Democrats made specific reference to the Roberts quote. 

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"It's a little hard to see home plate from right field," Sen. Dick Durbin, D-Ill., said. Then he added "if being a Supreme Court justice were as easy as calling balls and strikes, we wouldn't see many five-and-four decisions in the court."

"If judging were that mechanical, we would not need nine Supreme Court justices," added Sen. Sheldon Whitehouse, D-R.I.

The analogy speaks to the overall role a judge is supposed to play in presiding over a case, but Democrats appear ready to use the line as a counter-balance to Republican efforts to tarnish Sotomayor's standing with numerous references to her "wise Latina" remarks that she's made in numerous speeches in recent years.

Sotomayor may be a more favorable judge for conservatives," suggested Sen. Charles Schumer, D-N.Y.. 

"Judge Sotomayor's record bespeaks judicial modesty, something that our friends on the right have been clamoring for in a way that no recent nominees has," Schumer said. 

But unlike his colleagues who were dismissive of the umpire analogy, Schumer said Sotomayor has been a better umpire.

"Any objective review of Judge Sotomayor's record on the Second Circuit leaves no doubt that she has simply called balls and strikes for 17 years far more closely than Chief Justice Roberts has during his four years on the Supreme Court," Schumer said.

After the end of the hearing's first day, Sen. Jeff Sessions, R-Ala., the top Republican involved in the hearing said he did not think the Democrats strategy was legitimate. Roberts, he said, "is philosophically committed to restraint" and he blasted Democrats for what he called a "result-oriented argument."

There was so much talk about Roberts that Sen. Tom Coburn, R-Okla. all but apologized to Sotomayor for the spotlight shining elsewhere. 

"I also wanted to note that I thought this was your hearing, not Judge Roberts' hearing," he said.

But the issue over a judge's proper role in court may prove to play a larger role in the hearing than anything specific to Sotomayor, whose confirmation is not in doubt. 

The diversion was a turn Sessions seemed to welcome Monday 

"I think in this whole confirmation process we need to talk about what activism is," he said.