This editorial in The Times discusses the push for Schumer-Van Hollen.

A measure to be offered as early as this week would require trade associations, unions and nonprofit groups to clearly identify who is paying for ads designed to slant opinion for and against particular candidates. It also would restrict campaign spending by American corporations with partial foreign ownership. Another proposal would require that political expenditures be approved by corporate shareholders.

. . .

Supporters of the Bipartisan Campaign Reform law of 2002 should be in the vanguard for disclosure. Chief among them is Senator John McCain, who has had too little to say on the subject as he wages a close re-election fight against a right-wing candidate.