Want more proof that we're in the midst of the most expensive presidential campaign in history? Mitt Romney, Barack Obama and their supporters are on pace to raise more than $1 billion each.

The New York Times says financial disclosure forms show Obama and the Democrats have already topped $1 billion, while Romney and the Republicans are up to $954 million.

The sources of that money, raised over the course of a deeply polarizing campaign, echo the sharp divisions between the two men and their parties over issues like abortion rights, the role of government in regulating industry and the country's economic future.

Wall Street has invested more heavily in Mr. Romney, a former financier who has pledged to repeal Mr. Obama's new financial regulations, than in any presidential candidate in memory. Employees of financial firms had given more than $18 million dollars to Mr. Romney's campaign through the end of September and tens of millions more to the "super PACs" supporting him.

Insurance companies, doctors and law, accounting and real estate firms are giving less to Mr. Obama and the Democratic National Committee than they did four years ago, according to data from the Center for Responsive Politics.

Yet donors in other industries have stepped in. With Mr. Obama making repeated trips to Silicon Valley and holding round tables with executives there, the technology industry has donated about $14 million to the president and the Democrats, substantially more than in 2008.

Retirees, the biggest single source of money for both sides, have given the Democrats much more than they did four years ago, as have employees of women's groups, retailers and hospitals and nursing homes.