President Barack Obama signed into law on Thursday a bipartisan bill to kickstart small business growth, and he promised rigorous oversight to make sure the measure does not harm investors, as critics have warned.

The bill, which was drafted in the Republican-controlled U.S. House of Representatives, will make it easier for small companies to raise capital and make an initial public offering.

It made unusually quick progress through a generally gridlocked Congress, with Democrats and Republicans eager to be seen backing business growth in an election year with unemployment still above 8 percent.

"For startups and small businesses, this bill is a potential game changer," Obama said at a signing ceremony at the White House. "Startups and small business will now have access to a big new pool of potential investors, namely the American people."

The bill will make it easier for companies to solicit private investors and it relaxes filing requirements associated with initial public offerings. It also allows startup companies to engage in crowdfunding, in which investors take small stakes in companies over the Internet.

A group of Senate Democrats, regulators and investor advocates have expressed concerns that the law will roll back critical shields that protect unsophisticated investors from securities fraud.

Seeking to blunt such criticism, Obama directed his administration, including the Justice Department, to keep a close eye on the bill's effects and said the Securities and Exchange Commission will play an important role in implementing the bill.