The poll shows Shaheen leading Brown, a carpetbagger who only moved to New Hampshire this year to run for Senate, by only 46 percent to 44 percent, within the poll's margin of error.
Brown, who must still win the GOP nod, is hardly a formidable challenger. So far his best defense of his itinerant political ways has been: "Do I have the best credentials? Probably not. 'Cause, you know, whatever."
So Shaheen should be crushing Brown. And ardent Democrats say she still is, citing other recent polling showing her with a wider lead and calling the latest Granite State Poll an outlier. Maybe. We do still need follow-up surveys to determine whether the New Hampshire race is really this close.
But University of New Hampshire political scientist Andrew E. Smith, who conducted the survey, is standing behind the results and argues they are the direct result of Obama's plunging national approval ratings.
"I think it's an Obama drag," Smith told The Boston Globe.
The poll found that just 38 percent in New Hampshire approve of how Obama is handling his job, a 7 point drop from the previous month. "Neither Brown nor Shaheen had any control of that; they're just at the mercy of what's happening nationally," Smith told the Globe.
If New Hampshire really is flipping into the toss-up category it would significantly increase Republicans' changes to pick up the six seats they need to retake the Senate and begin peppering Obama with must-pass spending bills larded up with proposals to roll back Obamacare provisions, environmental rules and other items.
Senate Minority Leader Mitch McConnell told Politico this week that if the GOP does retake the Senate the party will take a highly confrontational approach, daring Obama to sign these spending bills with policy riders attached or risk shutting down the government.
There is a chance this is just campaign rhetoric. And any majority Republicans gain will be slim. The party has been badly burned by shutdowns and debt ceiling near misses in the past. But the betting inside the GOP is the dynamic will be very different in 2015 if bills actually reach the president's desk and shutdowns can be directly tied to his refusal to sign them.
The playing field already tilts toward a GOP takeover. The party is likely to win open Democratically held seats in Montana, West Virginia and South Dakota, putting them halfway to the total they need. They would then need less than half of the remaining toss-ups in Democratic seats in Alaska, Arkansas, Colorado, Iowa, Louisiana, Michigan and North Carolina.
Read MorePresident Obama: US will be vigilant, relentless against terrorists
There is a chance if Obama cannot turn around his precipitous slide that a true wave election could form driving all those seats into Republican hands while also flipping New Hampshire and possibly even Minnesota, Oregon and Virginia.
With the economy slowly but steadily improving such a big wipeout for Democrats seems relatively unlikely. But a GOP gain of six or more seats is still a slight probability.
So what can Obama do to slow Republican momentum? Appearing engaged and attentive to his job would be a good start.
Obama seemed miffed to have to interrupt his vacation to deal with the crises in Ferguson, Missouri, and the Middle East. But he seemed really happy golfing with Alonzo Mourning and other pals. That led to brutal coverage and headlines like the New York Daily News'
this week. And it left even ardent Democrats grumbling that the president better start caring more about "optics" and his critics.
The White House also had to deal this week with a fiasco over the release of information about a failed raid to rescue Foley earlier this year. The administration released details of the raid saying they had no choice because word of it was already leaking. And just who was leaking it and why?
Read MoreObama: Will 'see that justice is done' for Foley killing
It seemed clear it was administration officials wanting to make clear they had done something to try to get Foley back. Defense Secretary Chuck Hagel then embarrassingly called the mission to retrieve Foley "flawless." Except for the part about Foley not being there. Oops.
Still, on the substance, Obama has some things going for him. Ferguson has quieted down and strikes against ISIS have pushed the well-funded terrorist state back a bit. If Obama returns to Washington and leads even more successful attacks on ISIS while rolling out a robust executive action agenda on tax inversion deals and immigration he could get Democrats fired up again and stop the erosion in his poll numbers.
But that would require him to both care about his critics' concerns and start doing things a little bit differently.
—By Ben White. White is Politico's chief economic correspondent and a CNBC contributor. He also authors the daily tip sheet Politico Morning Money [politico.com/morningmoney]. Follow him on Twitter @morningmoneyben.