"We can transform the summit from just an annual meeting into an unstoppable progressive partnership to secure the global change the world needs," Brown said.
The goal for the meeting is twofold: agree on a way forward to manage the current global economic crisis and develop a plan to prevent future crises.
But those two goals pose a significant challenge for Obama. Though the other G20 nations are looking to the United States to take the lead, their leaders are not shy about disagreeing with the American approach.
Leaders from France, Germany, Russia and China arrive at the summit in London armed with skepticism about the American economy and the Obama administration's plans for recovery.
Many world leaders have publicly resisted Obama's call for global economic stimulus efforts.
Last week, Czech Prime Minister Mirek Topolanek deemed the Obama administration's economic policies "a way to hell."
"America is repeating the mistakes from the '30s. … Extensive stimuluses and calls for protectionism," said Topolanek who is also the current president of the European Union. "The worst about these steps is that they are intended to be permanent, which is a way to hell."
Brazilian President Luiz Inacio Lula da Silva pointed the finger at the United States and Europe and sparked considerable controversy when he said last week that the global economic crisis was caused by "white people with blue eyes."
White House officials have downplayed the disagreements.
"I think going into the summit, there's a broad consensus among the G20 as to what needs to be done in these areas to restoring growth and a regulatory reform efforts," said Froman. "Between the stimulus program, the financial stability program and its various elements and the regulatory reform agenda that [Treasury] Secretary [Timothy] Geithner laid out this week, the U.S. has taken significant steps on each of the elements of the overall agenda."
"The president and America are going to listen in London, as well as to lead. Many of the things that we've done over the past couple of weeks, and particularly just in the past week, demonstrate that America is leading by example," White House press secretary Robert Gibbs said Monday.
An ABC News/Washington Post poll out today shows Americans are increasingly confident about the economy, a potentially persuasive tool for Obama at the G20 summit.
Forty-two percent of Americans now say that the country is moving in the right direction, up from 19 percent before Obama took office in January and 8 percent in October.
Thirty-six percent of Americans still say the economy's getting worse, but that is dramatically lower than the 62 percent who said that in January and a record 82 percent in October.
At the end of the week, Obama will attend a NATO summit that will be jointly hosted by France and Germany. The war in Afghanistan and the situation in Pakistan will be at the top of the president's agenda when he sits down with NATO allies and meets with French President Nicolas Sarkozy and German Chancellor Angela Merkel.