The jury of John Edwards’s peers is missing one highly relevant demographic: His peers do not, it turns out, include any women of a certain age — not one, anyway, who looks within shouting distance of the 62 years old Elizabeth Edwards would be today.

Of course, as the prosecution stressed during the opening arguments of the two-time presidential candidate’s criminal trial Monday, Johnny Reid Edwards — his full given name — is not on trial for two-timing his dying wife.

But the campaign finance case against him does turn on whether he knowingly violated the law by using more than $900,000 in gifts from two wealthy donors to keep his presidential hopes alive by covering up his affair with campaign aide Rielle Hunter.

“It’s often said ambition is an important quality in a politician,’’ prosecutor David Harbach began. “But like many things in life, too much can be dangerous.”

In pursuing his presidential ambition, the prosecutor said, Edwards didn’t care who he hurt or what he broke — “not other people, not family, not the law.’’

“In the heat of his second race’’ for the top office in the land, Harbach said, “he was also in the heat of an affair’’ with a woman he’d hired so they could travel together.

But he was desperate to keep her happy and silent, especially after she became pregnant, Harbach said, “because his mistress was a loose cannon with no source of income, and he knew it.”

Prosecutors need to prove that he intended to break the law: “He made a choice to accept hundreds of thousands, and he made a choice to break the law; that’s why we are here,’’ said Harbach, as Edwards’s daughter Cate, seated behind the former politician in the courtroom, crossed her arms over her chest.

But his defense suggested that campaign law is so complicated that it will be hard to prove he even knew what it was.

Physically, the defendant is curiously unaltered from the boyish-looking man who talked about “the two Americas” of haves and have-nots during his first presidential run in 2004. He has only a few gray hairs and still wears the Bruno Maglis he favored on the trail. But he wasn’t wearing his late son Wade’s Outward Bound pin on his left lapel, as he used to do.

Edwards is clearly an active participant in his defense and was constantly conferring with his attorneys at the defendant’s table during the final phase of jury selection — openly sizing up potential jurors and repeatedly motioning for Cate, who like him and her late mother is a lawyer, to come close so he could tell her something.

Also in the courtroom were his elderly parents, seated on cushions on the wooden benches. His father, whose humble roots as a millworker were a staple of Edwards’s stump speech, warmly greeted his son, patting both of his arms. At one point before the jury came in, Edwards got a Styrofoam cup of water for his mother.

This isn’t Watergate, but Edwards’s defense attorney repeatedly told the jurors to “follow the money” — and promised that if they did, they’d see that it was former Edwards aide Andrew Young who “milked” heiress Bunny Mellon for money for Edwards, giving some to Hunter but spending most of it on a $1.5 million house for himself.

Then, the defense said, Young went to another Edwards friend and donor, Fred Baron, for reimbursement for money he claimed to have spent on Hunter but hadn’t.

Edwards faces up to 30 years in prison and $1.5 million in fines on six counts — federal charges that include conspiracy, false statements and taking illegal campaign contributions.

Defense attorney Allison Van Laningham referred to her client as “a man who has committed many sins but no crimes. ”

She said that because Mellon and Baron paid gift taxes on the money, there wasn’t any conspiracy to break the law.

Just as the defense acknowledged that it has an unlikable cur of a client, the prosecution acknowledged that it has a badly flawed star witness in Young, who like Edwards is an accomplished liar, at one point claiming Edwards’s daughter with Hunter as his own.

“Since he can no longer make money being for John Edwards,’’ Van Laningham said, “he wants to make money being against him.’’

When Young took the stand Monday, he spoke at length about how he’d wormed his way into Edwards’s life — driving him everywhere, picking up his dry cleaning, changing the light bulbs in his home, doing anything at all that needed doing, really.

In the end, the case will turn on which worm turned on the other, and which one we believe.