A top Democrat said Saturday that the U.S. government plans to back troubled mortgage finance companies Fannie Mae and Freddie Mac.

Rep. Barney Frank, the chairman of the House Financial Services Committee, said in a statement that U.S. Treasury Secretary Henry Paulson "intends to use the powers that Congress provided" in a law passed in July to keep Fannie Mae and Freddie Mac stable and functioning.

But Frank said he did not "know the details of the proposed interventions," and a Treasury spokeswoman declined to comment.

The Wall Street Journal website, citing unidentified people familiar with the government plan, said the government is expected to take control of the two companies, at least temporarily, and invest public money in the shareholder-owned companies.

The two companies are vital cogs in the U.S. mortgage market. They buy mortgages from lenders such as banks, and repackage and sell them as investments around the world.

By buying the mortgages from lenders, they enable the lenders to make new loans.

With files from the Associated Press