The Chamber of Commerce hopes to more than double its grass-roots activists around the country from 5.5 million to 12 million in the next year, leaders of the pro-business group said in a conference call with members Wednesday afternoon.

The chamber, the world’s largest business federation and a longtime Washington fixture, is turning its attention beyond the Beltway in an effort to develop a “larger, more significant impact on Capitol Hill,” said Bill Miller, the group’s vice president of political affairs.

New recruits will focus their attention on the fiscal 2012 budget and reducing the federal deficit, Miller said, but he offered no specifics on strategy or how much money the chamber would put behind the ramped-up campaign.

The group wants to increase its presence on the state level, opening new offices in Congressional districts that have what he described as particularly “business sympathetic” constituents.

Despite continued economic growth, the top factor keeping small businesses from hiring is uncertainty about new federal regulations, Miller said, citing a chamber survey that found confidence among small-business leaders at a five-month low in April.

“They fear what D.C. will roll out next,” he said. “New businesses are reluctant to get into the game until they know what the rules are.”

The implementation of the health care and financial regulatory overhauls and rising gas prices are also to blame for the decline in small businesses’ confidence, he added.

As part of its expanded outreach program, the group will host a small-business summit in Washington, D.C., in May, a governors summit in June and a jobs conference in July.