The generally conservative-leaning Rasmussen daily tracking poll on Monday gave President Obama his biggest lead over presumptive Republican nominee Mitt Romney since May.

Obama leads Romney, 47 percent to 44 percent, in the general-election matchup. Rasmussen notes that the 47-percent mark is also Obama's highest level of support since March.

That means, in exactly a month, the presidential race has swung 8 percentage points. On July 27, Romney led Obama 49 percent to 44 percent.

The poll looks to swing with the start of the Republican National Convention on Tuesday, where Romney will likely see the traditional convention "bounce."

But it suggests that Romney has lost some major ground in the past month. Some things that may have contributed: Romney's generally disastrous overseas trip and the fallout of Missouri Rep. and Senate candidate Todd Akin's controversial comments on rape, pregnancy and abortion.

The poll also shows that even after Romney picked Paul Ryan as his running mate, the race has moved 7 points in Obama's favor.