WASHINGTON — After decades of work for some of this country’s most powerful lobbying firms, Lanny Davis, the lawyer who once helped defend President Bill Clinton from impeachment, is suddenly scrambling to defend himself.

Since leaving the White House, Davis has built a client list that now includes coup supporters in Honduras, a dictator in Equatorial Guinea, for-profit colleges accused of exploiting students and a company that dominates the manufacture of additives for infant formula. Earlier this month, he agreed to represent the Ivory Coast strongman whose claims to that country’s presidency have been condemned by the international community, and may even set off a civil war.

Davis withdrew from his $100,000-a-month contract with the Ivory Coast on Wednesday night, saying that the embattled government refused to accept his suggestion to talk to President Barack Obama. Still, his role in West Africa has stoked criticism that Davis has become a kind of front man for the dark side, willing to take on some of the least noble companies and causes.

Many lobbying firms have clients with checkered records. Indeed, those are the people who need help the most. But many activists — and even some government officials — said the list of clients in Davis’ firm stands out.

“You look at who he represents, and the list is just almost unseemly, tawdry,” said Meredith McGehee, a lobbyist for California WIC Association, which represents agencies that serve poor women with infant children, and who faced off against Davis this year in the fight over baby formula, which his client won.

Davis says he is aware of the criticism, particularly since his representation of the Ivory Coast became an issue. And he is pushing back. He says he’s lining up State Department officials, members of Congress and business leaders to testify about how much he’s helped them.