A former professional basketball player who helped start a charter school in Harlem this year, Kevin Johnson, is on a swing through New York to raise funds for his bid for mayor of Sacramento, Calif., just as his campaign is being rocked by word that he has been barred from doing business with the federal government.

The agency that runs the AmeriCorps program, the Corporation for National & Community Service, announced yesterday that Mr. Johnson, a Sacramento community group he founded, St. Hope Academy, and a former head of the group’s neighborhood corps, Dana Gonzalez, were suspended from participating in federal contracts or grants pending the outcome of an ongoing investigation into the improper use of federal grant money.

The agency’s inspector general, Gerald Walpin, said in a statement that his initial report “cited numerous potential criminal and grant violations, including diversion of federal grant funds, misuse of AmeriCorps members and false claims made against a taxpayer-supported Federal agency.” According to government documents, investigators found that AmeriCorps members drove Mr. Johnson to personal appointments, washed his car, and did personal errands. Also, they said the federally sponsored corps members were used to staff a store St. Hope Academy ran and to perform “routine clerical and cleaning activities outside the scope of the grant.”

Mr. Johnson declined to comment about the imbroglio during a $1,000-a-ticket fund-raiser for his campaign last night at an apartment on East 64th Street. Asked if the flap would affect his run for Sacramento mayor, he said, “No.”

Mr. Johnson’s campaign manager, Steven Maviglio, stressed that the candidate has been cooperating with the federal inquiry. “We’re confident in the outcome,” Mr. Maviglio said.

Ventura Rodriguez, the principal of the St. Hope Leadership Academy, which opened on West 134th Street last month, said the federal action would not have an impact on the new school. “None whatsoever,” he said. “St. Hope Academy is a completely separate board of trustees and financially separate from St. Hope Leadership Academy. … All the funding is from New York State. There’s no money from the federal government or from St. Hope.”

Still, it’s clear Mr. Johnson played a key role in getting the Harlem school off the ground. Press releases from St. Hope in Sacramento claimed credit for and touted the approval of the New York school. In addition, Mr. Johnson was the featured speaker at the school’s opening last month.

“Obviously, there’s a connection,” Mr. Rodriguez said

An official with the city’s education department, who asked not to be named, said the agency was monitoring the situation but that state law requires groups that run New York charter schools to be freestanding entities.

One of the specific abuses found in the federal investigation involved taking AmeriCorps members on a trip to New York in 2006 to recruit students for the new Harlem school.

According to federal records, St. Hope Academy received about $800,000 in federal funds between 2004 and 2007 for tutoring and community programs in Sacramento. “When you instead take the AmeriCorps members to New York for a purpose not within the grant, you are misusing the members and diverting the funds from the purposes intended,” Mr. Galpin, the inspector general, told The New York Sun yesterday.

Mr. Galpin denied, when asked, that the probe or the timing of the suspension had anything to do with Mr. Johnson’s mayoral bid. “Any local political activity is totally irrelevant to the performance of my office’s obligation to protect taxpayers,” the investigator said.

At the Harlem school’s opening last month, Ms. Gonzalez, who was also personally barred from contracts this week, identified herself to a Sun reporter as a member of the board of the new school. She could not be reached for comment yesterday. The new executive director of the St. Hope Academy, Rick Maya, said she left her job as the new school developer for the Sacramento group on August 1.

Despite claims that St. Hope Academy has no legal connection to the Harlem school, the California group registered in October 2007 with the New York Department of State as a out-of-state entity doing business in New York. Mr. Maya said he could not explain the registration.

A spokeswoman for the U.S. Attorney’s Office in Sacramento, Lauren Horwood, confirmed that her office is mulling a report from Mr. Galpin. “We received the report in August. Our office is still reviewing it,” she said. She said she could not predict how long the review would take.

Mr. Johnson, 42, a former point guard for the Cleveland Cavaliers and the Phoenix Suns, is considered a pioneer in the charter school movement. He founded St. Hope as an after-school program in 1989. Beginning in 2003, he opened six such charter schools in his native Sacramento. He stepped down as the president and CEO of St. Hope in March.

“We like him because he’s got the potential to bring a lot of energy and excitement to the issue of education,” an organizer of last night’s fund-raiser, Joseph Williams of Democrats for Education Reform, said. “Here’s a guy who went off to the NBA and could have gone on to do anything else and instead went back to his community and identified education as an important part of rebuilding his community.”

Mr. Williams cast Mr. Johnson as in the same mold as Mayor Cory Booker of Newark and Mayor Adrian Fenty of Washington, both of whom have stressed improving schools. “We’re very interested in the movement nationally towards mayors grabbing the mantle of education reform,” Mr. Williams said.

Mr. Johnson is challenging Mayor Heather Fargo in November. Both are Democrats. Ms. Fargo backed Senator Clinton in the primary, while Mr. Johnson backed Senator Obama. Last night’s event doubled as a fund-raiser for Mr. Obama and featured an education adviser to the Democratic presidential nominee, Jonathan Schnur.

Mr. Johnson is still garnering support from his former colleagues in the NBA. Suns center Shaquille O’Neal is scheduled to speak today at a lunchtime fund-raiser in Sacramento for Mr. Johnson’s campaign and at a dinner gala for St. Hope Academy.

A Washington lawyer who specializes in federal contracting, Frederic Levy, said Mr. Johnson’s suspension could complicate the city’s effort to win grants if he becomes mayor and the bar remains in place. Mr. Levy said grant applicants are required to certify that no “principal” is barred or suspended, or to explain why they cannot do so. “That might be a basis for denying those monies,” the lawyer said, though he added that agencies have flexibility in enforcing the ban.