Click here to watch "17 Million."

After winning the Puerto Rico primary this Sunday, Hillary Rodham Clinton wasted no time in arguing to the superdelegates that she now leads the popular vote, with over 17 million primary voters having cast ballots in her favor. While many Democrats dispute Clinton's count, which includes votes from Florida and Michigan and estimates from some caucus states, that hasn't stopped her from touting the figure in a new TV ad running today and tomorrow in South Dakota and Montana, sites of the final two Democratic primary contests.

"17 Million" (subscription) echoes the appeal of other recent Clinton advertising, rallying local viewers by telling them their votes are still important while signaling to outside observers that she isn't leaving the fight. Asserting that she has won more primary votes than any other candidate, the spot goes on to cite this support itself as reason for South Dakota and Montana voters to pull the lever for Clinton. "Some say there isn't a single reason for Hillary Clinton to be the Democratic nominee," an announcer says. "They're right. There are over 17 million of them."

Whether or not "17 Million" persuades Democratic voters, it offers a distillation of what could be Clinton's final appeal to her party's establishment: that she's won more votes, in more important states, and simply by staying in the race has proved she's the most effective candidate to address tough issues such as Iraq and the economy. With Barack Obama less than 50 delegates away from the nomination, according to CNN's estimate, and primary voting finally finished on Tuesday, she's under more pressure than ever to make her case.