Loopholes that lobbyists for foreign clients sometimes use to keep their activities under wraps would be closed under legislation that two Democratic senators are expected to offer on Thursday.

Lobbying by foreign agents  and the lack of disclosures about their activities  is an issue that has dogged the presidential campaign of Senator John McCain, who in recent weeks has seen aides resign because of their ties to foreign governments and private interests.

The legislation, by Senators Charles E. Schumer of New York and Claire McCaskill of Missouri, would require lobbyists who work for foreign-owned companies to disclose more about those relationships than they currently do.

It also would require those who meet with American officials outside the country on behalf of foreign politicians to register as lobbyists, a step that existing law does not require.