Major liberal donors are demonstrating their willingness to fund a new shadow Democratic Party, according to reports filed Friday by a network of nominally independent organizations committed to defeating President Bush in November. At the same time, momentum to bar their activities gained new strength. On Thursday, the legal staff of the Federal Election Commission proposed regulations that could choke off the groups' plans, with backing from an alliance of Republican Party leaders and campaign-watchdog groups. The reports filed Friday with the Internal Revenue Service and the FEC showed millions of dollars flowing from unions, wealthy individuals, environmental groups and...