Shareholder support for disclosure of corporate political support continues to build.

The Center for Political Accountability, examining results of disclosure proposals for the 2010 annual meeting season, found that shareholder support for disclosure rose to a record 30.25% at 28 meetings.

Since 2004, about 200 disclosure resolutions have been submitted on corporate proxies.

Disclosure support at four companies was particularly strong: Coventry Healthcare, 46%; Express Scripts, 42%; CVS Caremark, 41.35%; Sprint Nextel, 41.2%, and Allstate, 39.7%.

Bruce Freed, President of the CPA, says the results indicate that “more and more (investors) are calling for an end to the secrecy that has cloaked corporate political spending and want accountability.”

He added: “When you consider that the majority of votes side with management as a matter of course, the substantial support from retail and institutional shareholders shows the broad support for political disclosure.”

The Center recently launched an online database that allows users to examine how specific companies treat political accountability and disclosure.

Corporate political campaign support has become a hot button issue this year, particularly in view of the January 5-4 decision by the U.S. Supreme Court removing limits on corporate and union spending on political ads.

Critics of the decision fear a deluge of corporate spending, prompting Democrats to seek to limit the decision and to require contributors to disclose their identities.  The legislation, labeled the DISCLOSE Act, passed the House 219 to 206 in late June, but backers had to make key concessions to achieve passage.  One change would exempt the National Rifle Association from the bill’s disclosure requirements. And opponents, led by the U.S. Çhamber of Commerce, have labeled the measure an assault on free speech.

Similar legislation introduced in the U.S. Senate faces an uncertain future, particularly in an election year.

Durbin’s initiative follows Google’s announcement that it had been the victim of cyber attacks aimed at gaining access to the email accounts of Chinese human rights activists. Google has said it is considering pulling out of China because of the attacks and what the company called “attempts over the past year to further limit free speech on the web.”

Only two weeks ago, U.S. Secretary of State Hilary Clinton called on American technology companies to make a “principled stand” against attempts at censorship.

Sen. Durbin, Chairman of the Judiciary Subcommittee on Human Rights and the Law, said his hearing next month will feature testimony from Google and other companies about their business practices “in internet-restricting countries,” as well as from high-ranking Obama Administration officials about the Administration’s efforts to promote internet freedom.

“I commend Google for coming to the conclusion that cooperating with the ‘Great Firewall’ of China is inconsistent with their human rights responsibilities,” Durbin said. “Google sets a strong example in standing up to the Chinese government’s continued failure to respect the fundamental human rights of free expression and privacy. I look forward to learning more about whether other American companies are willing to follow Google’s lead.”

Durbin’s letter asks each firm for details of its business in China, and what, if any, measures it will implement to ensure that its products and services do not facilitate human rights abuses by the Chinese government.

This week’s letter also follows up on a letter that Durbin sent last year, urging technology firms to join a voluntary code of conduct known as the Global Network Initiative (GNI). The code of conduct, which regulates the actions of technology firms operating in countries that restrict the internet, has been backed by Google, Microsoft, and Yahoo! and a number of leading socially responsible investment firms.

Durbin’s office said the list of companies that responded to his previous letter included Apple, AT&T, Cisco, Dell, eBay, Facebook, HP, McAfee, News Corp, Nokia, Nokia Siemens, Siemens, Skype, Sprint Nextel, Verizon, Vodafone, Websense.

According to Senator Durbin’s office, companies that did not respond to his previous letter were Acer, Juniper, Toshiba, Twitter; companies that “partially responded” to his previous letter were Fortinet, Lenovo, Motorola.