If Fox says it's so, it's so:

Mitt Romney has had a tough couple of weeks on the campaign trail -- and it shows in the latest Fox News poll. After a barrage of campaign ads, negative news coverage of his overseas trip and ongoing talk about his tax returns, Romney’s favorable rating and standing in the trial ballot have declined. As a result, President Obama has opened his biggest lead since Romney became the presumptive Republican nominee.

The president would take 49 percent of the vote compared to Romney's 40 percent in a head-to-head matchup if the election were held today, the poll found. Last month, Obama had a four percentage-point edge of 45 percent to 41 percent. This marks the second time this year the president has had a lead outside the poll’s margin of sampling error.

Obama’s advantage comes largely from increased support among independents, who now pick him over Romney by 11 percentage points. Some 30 percent of independents are undecided. Last month, Obama had a four-point edge among independents, while Romney had the advantage from April through early June.