The main pro-Hillary Clinton Hillary Diane Rodham ClintonHillicon Valley: FBI chief says Russia is trying to interfere in election to undermine Biden | Treasury Dept. sanctions Iranian government-backed hackers The Hill's Campaign Report: Arizona shifts towards Biden | Biden prepares for drive-in town hall | New Biden ad targets Latino voters FBI chief says Russia is trying to interfere in election to undermine Biden MORE super-PAC is opening up its war chest with a $5 million spending blitz to boost her in the Democratic presidential primary.

Priorities USA Action is launching a 60-second radio ad starting Friday in South Carolina through the Feb. 27 primary in the state that is backed by $500,000, according to the group.

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“We all worked hard in 2008 and 2012 to elect President Obama,” a person says in the ad. “And we’ve seen with our own eyes how Republicans have tried to tear him down every step of the way.

"We can’t let them hold us back. We need a president who will build on all that President Obama has done," the ad continues, before noting that Obama "trusted" Clinton to be secretary of State.

That's only the opening salvo, with the super-PAC planning a $4.5 million effort targeting voters through mail, online and on the radio. The group hopes to target voters in all states that hold March primaries on a rolling basis.

Priorities USA Action will focus on those states with early in-person voting including Georgia, Arkansas, Oklahoma, Tennessee, Texas, Louisiana, Florida, Illinois, North Carolina, Ohio and Arizona.

The Washington Post, which first reported the new efforts, noted that group is focusing on getting women, African-American and Hispanic voters to also show up in the primary and general election to boost Clinton.

Sen. Bernie Sanders Bernie SandersMcConnell accuses Democrats of sowing division by 'downplaying progress' on election security The Hill's Campaign Report: Arizona shifts towards Biden | Biden prepares for drive-in town hall | New Biden ad targets Latino voters Why Democrats must confront extreme left wing incitement to violence MORE (I-Vt.) is also making a play for those key demographic groups in the closer-than-expected Democratic race, and hopes to cut into Clinton's lead in South Carolina after his huge win in New Hampshire.

Sanders's campaign decried the spending by Priorities USA, with campaign manager Jeff Weaver saying in a statement that "it is truly unfortunate that the largest pro-Clinton super PAC has decided to infect the Democratic primary process with its haul of Wall Street cash."

Clinton sought to distance herself from the group while sparring with Sanders over role of PACs during a debate Thursday night. "It's not my PAC," Clinton maintained, noting it was initially set up to support Barack Obama Barack Hussein ObamaThe Hill's 12:30 Report - Presented by Facebook - Don't expect a government check anytime soon Trump appointees stymie recommendations to boost minority voting: report Obama's first presidential memoir, 'A Promised Land,' set for November release MORE.

Priorities said last month that it ended January with $45 million in the bank.

- This story was updated at 3:22 p.m.