Bill Clinton, Katy Perry headline star-studded Hillary rally

The former president kicked off the campaign event, playfully discussing his desire to return to the White House.
"I am tired of the stranglehold that women have had on the job of presidential spouse," Bill Clinton said. 
He touted his wife’s record and qualifications, as well as her goals of securing the economic recovery and ensuring women get equal pay for equal work and that health care includes mental care. 
Clinton also mentioned the next president would appoint between one to three Supreme Court justices. 
He drew a contrast between Hillary Clinton and Republican contenders, saying he "was proud to be a Democrat" after watching the last Republican debate and Thursday's 11-hour Benghazi hearing, and urged Americans to "stop rewarding the strategy of destruction." 
Pop star Perry followed the former president, performing a medley of hits, including "Roar' — a song Hillary Clinton's campaign has adopted as an anthem.
Perry also performed "Wide Awake" and “Firework,” as well as "America the Beautiful." 
As the pop star wrapped up, Hillary Clinton herself make a surprise appearance, invoking Perry’s most popular song by saying, “Sometimes it's important, you just have to roar.” 
She urged attendees to join the campaign and sign up to volunteer in Iowa, which is holding the first presidential caucus in February. 
"We are geared up and ready to go! We're going to fight until the very end of this campaign, for you and for your families, for fairness, for justice, for the kind of America that every one of you deserves!" Clinton said to cheers. 
She also expressed gratitude to her husband for his speech.
"I have to say, it's pretty special to have the 42nd president here with me," she said.  
The appearance comes hours before the Iowa Democratic Party’s Jefferson-Jackson dinner, which is seen as a key test for presidential contenders. President Obama's speech at the dinner marked his breakaway moment in 2007. 
Clinton’s 2016 primary opponents, Sen. Bernie Sanders (I-Vt.) and former Maryland Gov. Martin O’Malley, will speak at the dinner as well.