NBC/Marist polls: Obama leads close swing-state races

New battleground polling out this morning from NBC News and Marist College:

President Barack Obama holds a narrow advantage over presumptive Republican nominee Mitt Romney in three of the most pivotal presidential battleground states — Florida, Ohio and Virginia — according to new NBC-Marist polls. But in each of these states, Obama's share of the vote is below the 50 percent threshold usually considered safe haven for an incumbent president, and Romney has narrowed the margin in these three battlegrounds since earlier this year. In Florida and Virginia, Obama leads Romney by identical 4-point margins, 48 percent to 44 percent … In Ohio, the president is ahead by 6 points, 48 percent to 42 percent.

As NBC points out, those are tighter margins than in the network's last round of swing-state polling. Democrats are also up in the Virginia, Florida and Ohio Senate races, though by small gaps that indicate all three are likely to be close in November.

The Obama-Romney Florida number is 10 points off from the snapshot Quinnipiac University delivered yesterday, showing Romney up 6 points. Democrats questioned the composition of that poll; the larger takeaway may be that state- and national-level polling will continue to vary without changing the underlying reality that this is a very competitive race.