In 2013 conventional political wisdom pinned Attorney General Kathleen Kane as a rising star among Pennsylvania Democrats. She was plugged as the woman with the best chance of unseating Republican Senator Pat Toomey.

Three years later, Toomey is indeed in a political dogfight, but not against Kane, who is now headed to jail.

Once the Keystone State's top prosecutor, Kane is now a convicted felon and will spend the next 10 to 23 months behind bars for leaking grand jury documents in a scheme to embarrass her political rivals. During sentencing Monday, Judge Wendy Demchick-Alloy labeled Kane a "neophyte" and a "politician consumed with her image." But long before her conviction, she was described much differently.

President Bill Clinton endorsed Kane, who had worked on his wife's 2008 presidential campaign, as "a great Democrat who understands that an Attorney General's job is to stand up for consumers and people." Emily's List President Stephanie Schriock defined her as "a progressive fighter." And Pennsylvania liberals christened Kane "a rising star."

While those statements seem out of place now, at the time, they punctuated the first chapters of what could've been an impressive career.

An assistant district attorney, she defeated Rep. Patrick Murphy in the party's attorney general primary in 2012. She then thrashed her Republican challenger by nearly 15 points that November, becoming the first Democrat and the only woman ever to win the attorney general's office in the state. She won more votes than any other candidate on Pennsylvania ballots that year, including President Obama.

A year into the job and Kane won national attention for refusing to enforce Pennsylvania's gay marriage ban. She also reopened an investigation into Republican Gov. Tom Corbett's handling of the Penn State sexual assault scandal from when he had held her post.

Before a grand jury extinguished her meteoric rise, sources close to the attorney general reported that she was "pretty serious" about mounting a bid for Senate. And she might well have won, or so the polling seemed to suggest. In a December 2013 poll by PPP, Kane enjoyed a 4-point advantage over Toomey, a 46 to 42 percent lead.

The scandal broke a year later, ending all speculation about a Senate campaign. Instead she began preparing her defense against nine criminal charges including conspiracy and perjury.

The most recent poll by Emerson College has Toomey narrowly leading Katie McGinty, a lobbyist and a former Clinton administration and Pennsylvania environmental official, by three points.

Philip Wegmann is a commentary writer for the Washington Examiner.