WASHINGTON — A California venture capitalist who donated lavishly to major politicians of both parties — from former President Barack Obama and Hillary Clinton to President Trump — has agreed to plead guilty to violating lobbying, campaign finance and tax laws, prosecutors said Tuesday.

Imaad Zuberi, 49, had donated lavishly to Democrats before abruptly pivoting and donating more than $1.1 million to committees associated with Mr. Trump and the Republican Party in the three months after the 2016 presidential election. He was the only donor named by federal prosecutors in Manhattan in a subpoena issued in February to Mr. Trump’s inaugural committee, to which his California company, Avenue Ventures, had donated $900,000.

The charges announced Tuesday are not related to his donations to support Mr. Trump. But if Mr. Zuberi cooperated with prosecutors, it could have ripple effects into other investigations into contributions to Mr. Trump’s inauguration, including of whether foreigners illegally funneled money to it in hopes of buying influence over American policy.

Mr. Zuberi was charged with making nearly $1 million in illegal campaign donations from April 2012 through October 2016, including some funded by foreign sources, as part of a scheme to gain access to American politicians for foreign clients. He was also charged with falsifying records filed with the Justice Department under the Foreign Agents Registration Act to conceal his lobbying for Sri Lanka to help burnish the country’s reputation in Washington amid human rights concerns. And he was charged with failing to report and pay taxes on $5.65 million he was paid for the Sri Lankan lobbying campaign, much of which, prosecutors say, he diverted for his own personal use.