The law, pushed through mainly by Democrats in Washington's deeply partisan environment, comes almost two years after the near financial meltdown in 2008 in the United States that was felt around the globe. The legislation gives the government new powers to break up companies that threaten the economy, puts more light on the financial markets that escaped the oversight of regulators and creates a new agency to guard conssumers in their financial transactions.

Obama described them all as commonsense reforms that will help people in their daily life — signing contracts, understanding fees and assessing risks.

To a burst of applause, the president said: "Because of this law, the American people will never again be asked to foot the bill for Wall Street's mistakes."

In the midst of a heated election season for many lawmakers who face voters in November, Obama sought to put the complex law in consumer-oriented terms. He said it would help root out fine print and hidden fees for people, and provide deeper scrutiny of the sophisticated financial transactions on Wall Street.

Republicans portray the bill as a burden on small banks and the businesses that rely on them and argue it will cost consumers and impede job growth. Republican Rep. Darrell Issa called Obama's bill-signing a "charade" that ignored the root causes of the financial crisis.

The president said otherwise. He argued that a crippling recession was primarily caused by a breakdown in the financial system that cannot be allowed to happen again. "I proposed a set of reforms to empower consumers and investors, to bring the shadowy deals that caused this crisis into the light of day, and to put a stop to taxpayer bailouts once and for all," Obama said to supporters. "Today, thanks to a lot of people in this room, those reforms will become the law of the land."

In a note of irony, Obama signed the bill with great fanfare in the massive Ronald Reagan Building, named after a president who championed deregulation. The president was joined by scores of consumer advocates, state and local government officials, business owners and executives, and members of Congress who supported the bill. Obama singled out for praise Sen. Chris Dodd and Rep. Barney Frank, both Democrats, who shepherded the bill through Congress.

The law also assembles a powerful council of regulators to be on the lookout for risks across the finance system. Large, failing financial institutions would be liquidated and the costs assessed on their surviving peers. Borrowers will be protected from hidden fees and abusive terms, but also will have to provide evidence that they can repay their loans. The Federal Reserve will get new powers while at the same time coming under expanded congressional oversight.

"While President Obama pats himself on the back today, families and small businesses are bracing for yet another big-government overreach that will make it harder to create new jobs," said the House Republican leader, John Boehner.

Though Obama and his top officials urged Congress to pass the law while the memory of the 2008 financial meltdown was still fresh, many of the law's provisions will not take effect for at least a year as regulators scramble to write new rules and implement them.

Large Wall Street banks have welcomed some provisions in the bill, but have fiercely opposed others that would limit their banking business and cut into their profitability.