The measure requires campaign donors to identify themselves. Chris Bell says it will also address the consequences of a Supreme Court ruling in January, which lifted a long-standing ban on the corporate funding of political campaigns.
"The implications of the controversial 5 to 4 ruling known as Citizens United versus the Federal Elections Comission, are difficult to overstate," says Bell, who is with the U.S. Public Interest Research Group, a non-profit, political lobbying group which claims to advocate in the public interest.
"As it stands today, all organizations, corporations and unions are free to make unlimited political expenditures," he says. "Special interests are completely free to use their power and money to influence our elections with the American people left in the dark."
The DISCLOSE Act, he says, does more to strengthen disclosure and transparency than any measure in recent history.
"The DISCLOSE Act establishes new disclosure requirements for corporations, labor unions, advocacy groups and trade associations in order to provide voters with election spending information that allows them to test the accuracy of campaign statements and is essential if the free and open marketplace of ideas is to function properly."
"Here we sit in small-town Bangor, Maine, a small state. Everything's sort of small. but small is beautiful," says Rich Schweikert, who owns the Grasshopper Shop in Bangor - a business which he says does not make any political contributions.
Along with all the speakers at the event, he urged Maine Sens. Olympia Snowe and Susan Collins to help small businesses by supporting the DISCLOSE Act.
"They always say they love to support small business and how important small business is to our economy, now is their chance to stand up and really show that support," he says. "Now is their chance to stand up with the little guy, who can't spend the money big business can to influence elections."
The DISCLOSE Act was passed narrowly by the House in June this year. In July both Maine senators voted against the act in the Senate, helping to secure a Republican filibuster on the issue.
Barbara McDade, president of the League of Women Voters of Maine, hopes that this time round the senators can do some last-minute negotiating to come up with an acceptable version of the bill. "We know that the version that was passed by the House has some problems that our senators rightly see," she says. "But we know that they're in a position that they can negotiate, and we feel that they can work to bring about an agreement."
"The DISCLOSE Act is just the latest attempt by the government to limit our right to free speech guaranteed by the Constitution," says Tarren Bragdon, chief executive of the Maine Heritage Policy Center, a non-profit which advocates for fiscally-conservative policies.
He says political donors have a constitutional right to privacy. "The Supreme Court has repeatedly said that corporations and private entities also have a right to protect their donors from political retribution, and that's why that privacy is a right that is constitutionally recognized," he says.
The Maine State Chamber of Commerce has not taken a position on the DISCLOSE Act, unlike its parent organization, the U.S. Chamber of Commerce, which wrote to the Senate Wednesday morning to express strong opposition to the act, describing it as unconstitutional.
The Chamber's executive vice president for government affairs, Bruce Josten, says the act, in a number of instances, unfairly discriminates against business interests. "For example, would ban expenditures by American corporations that have a 20 percent foreign ownership, however there are no parallel bans in the legislation that would exist for unions," he says.
Observers say the DISCLOSE Act needs the support of just one Republican in Thursday's vote to break the filibuster.