Scarlett Johansson is backing Scott Stringer to become mayor by hosting two hip fund-raisers for the Manhattan borough president.

The uptown and downtown events aim at two different voting groups on the same night. On Oct. 3, from 5:30 p.m., ScarJo will host a fete at the Plaza Hotel apartments, with tickets ranging from $2,500 to $10,000. Then, at 7 p.m., the “Lost in Translation” star will spearhead a party at Sean MacPherson’s hipster-favorite Jane Ballroom in the West Village, where tickets will go for $50 to $1,000.

Sources tell us the star will also film Web campaign ads for Stringer.

PHOTOS: SCARLETT JOHANSSON

“Scott’s passion for New York is contagious,” she told us. “We share a love for this city’s diversity and culture. As a native New Yorker with a political history dedicated to community development, Scott’s priorities echo my own,” she said.

“When Scott is elected mayor, [we] can expect a representative who is focused on making New York a cleaner, greener city, providing affordable housing and preserving the integrity of our varied communities,” Johansson said.

The star and the candidate have family ties. Johansson’s brother, Hunter, worked for Stringer’s office in 2007, and Stringer met Johansson’s grandmother in the 1980s.

ScarJo is the latest in a growing list of celebrities endorsing candidates in the mayoral race. Anna Wintour and Lily Aldridge have written checks for Council Speaker Christine Quinn. Cynthia Nixon has said that Public Advocate Bill de Blasio would be a great mayor.

Stringer told us, “I am extremely grateful for Ms. Johansson’s support. She has a proven ability to energize young voters, and her participation in our campaign will go a long way towards engaging the multigenerational coalition needed to unify our city. I look forward to working closely with her in the years ahead.”