Senate Democrats are worried that the heavy spending of Republican-aligned outside groups in a handful of key races has added an unexpectedly steep barrier to their path back to the Senate.  

More concerning still for party strategists is the belief that the GOP’s cash edge shows no signs of shrinking, especially when Republican incumbents start spending heavily from their own cash reserves. In many races, the GOP candidates hold a gargantuan cash-on-hand advantage.  

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“Republican outside groups traditionally outspend Democratic ones,” said Sadie Weiner, spokeswoman for the Democratic Senatorial Campaign Committee. “And it’s no surprise that Republican dark money, special interest groups are spending big to save the Republican senators who are carrying their water in Washington.”  

Democrats need to win a net of four seats to take control of the Senate if Hillary Clinton wins the presidency — five if Donald Trump does. The party is optimistic about its chances, convinced that the unpopular Trump will lose badly on Election Day and take many down-ballot Republican candidates with him.  

But Democratic strategists also concede that a favorable national climate alone isn’t enough to knock off well-entrenched GOP incumbents. On-the-ground conditions like TV ad spending matter, too — and it’s on this front that the party is worried.  

Data provided by a Democratic source tracking ad buys, and confirmed by a Republican with knowledge of the TV ad spending, showed the largest spending edge for Republican outside groups in Ohio, where Republican Sen. Rob Portman faces former Democratic Gov. Ted Strickland.  

From January 2015 through until the end of this month, GOP-aligned outside groups have outspent their Democratic rivals $20.8 million to $12.67 million in the Buckeye State, according to the data.  

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The edge isn’t as significant elsewhere, but it still points to a GOP advantage. In Pennsylvania, which features a contest between Republican incumbent Sen. Patrick J. Toomey and Democratic nominee Katie McGinty , Republican outside groups have spent $11.5 million to the Democrats’ $9.9 million.  

Democrats are most vulnerable to losing a Senate seat in 2016 in Nevada, where Republican Rep. Joe Heck is trying to defeat former state Attorney General Catherine Cortez Masto. But through July, Republican groups have spent $7.2 million compared to $2.5 million on the Democratic side.  

In New Hampshire, however, Democratic groups have spent nearly as much as Republican groups — $11.3 million to the GOP’s $11.9 million. Republican Sen. Kelly Ayotte is taking on the state’s governor, Maggie Hassan, in arguably the most competitive Senate race of 2016.  

Many strategists believe that the majority could come down to the outcomes of these four races, all in general election battlegrounds in races that polls indicate are competitive.   

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The data includes spending only on TV ads, both broadcast and cable, and not digital ad spending. It also does not include spending on TV ads aimed at the primary stage, like contributions from the super PAC of P.G. Sittenfeld, who challenged Strickland in the Democratic primary in Ohio.  

It also does not include spending from the candidates themselves. But on this front, too, Democrats have reason to worry.  

Portman, for example, had $13 million on hand to end June, $9 million more than Strickland. Toomey holds a similar edge on McGinty, who emerged from a competitive primary in Pennsylvania nearly broke.  

“There’s a risk that Democrats waste what could be a potentially historic cycle if donors don’t step up,” said one Democratic strategist working for an outside group. “There are opportunities to win across the map but not if you get outspent 2:1.”

Complaints about money are commonplace from political operatives. And many of them openly acknowledge they’re often used as a tactic to persuade donors to give more money.    

And because of spending from nonprofit organizations, which often does not have to be reported to the Federal Election Commission, there are often disagreements about how much is actually being spent. Officials from the Portman campaign, for their part, repeatedly said at events during the Republican National Convention this week that Democrats have spent more money on the Ohio Senate race than any other.  

Contact Roarty at alexroarty@cqrollcall.com and follow him on Twitter @Alex_Roarty
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