U.S. Democratic presidential candidate Barack Obama and his wife reported on Wednesday an income of 4.2 million U.S. dollars in 2007 as a new national poll showed his lead has widened over his Democratic rival Hillary Rodham Clinton.
According to the tax returns released by Obama's campaign, the Illinois senator and his wife, Michelle, saw their income surge last year due to Obama's best-selling books "Dreams From My Father" and "The Audacity of Hope," profits from which amounted to around 4 million dollars.
The Obamas earned 991,296 dollars in 2006, according to the official record.
Other income sources included Obama's annual salary as a senator of 157,102 dollars, and Michelle's salary of 103,633 dollars as an executive officer at the University of Chicago Medical Center.
His campaign also said that the couple paid 1.4 million dollars in federal taxes and donated more than 240,000 dollars to charities.
However, their fortune falls far behind that of the Clintons, who have reported 20.4 million dollars in 2007, almost half of which were earned from former president Bill Clinton's speeches.
The total amount of the Clintons' income since they left the White House in 2001 has reached nearly 109 million dollars.
The two candidates are intensifying their campaigns ahead of the Pennsylvania primary slated for April 22, more than one month after the last contest.
So far, Obama still leads the race with 1,644 delegates who would vote for him at the party's nomination convention, compared to 1,498 in Clinton's count.
Despite his controversial comments about some small-town Americans, Obama has extended his lead over Clinton from 3 percentage points in March to 9 now, according to a CNN poll released on Wednesday.
The "poll of polls" drew the conclusion after an analysis of the surveys conducted between April 7 to 15 by Gallup and ABC/The Washington Post, among others.