That Huge Republican Cash Edge? It's in Senate Races, Not House Races.

Cumulative ad spending for the general election by each party in races rated as a tossup by the Cook Political Report.

Republicans have an enormous financial edge in this year's midterms. But with two weeks until the election, it is now clear that their spending advantage is overwhelmingly playing out only in the advertising battle for the Senate -- not the House.

In the seven Senate races that the Cook Political Report rated as tossups, Republicans are outspending Democrats on advertising by $947 million to $625 million. That is a breathtaking advantage of more than $320 million in the key races that could determine which party wins control of the Senate, according to a tally by AdImpact of ads that have been already been shown and future reservations.

It is a very different story in the House, though. Republicans still have an advertising advantage in the closest House races, but it is relatively narrow -- just a $14 million edge across the 21 races rated as tossups.

There are a number of explanations for the discrepancy.

Senate races generally attract more money and attention than congressional contests. Elon Musk's enormous spending on the Texas Senate race is also a factor: He gave nearly $170 million to super PACs backing Ken Paxton, the Republican Senate nominee there -- a huge injection of cash from one person.

But it is also appears to be an indication that both parties -- and their donors -- are viewing it as increasingly unlikely that Republicans will be able to hold onto their House majority. The battle to win control of the Senate, though, remains on a knife's edge. Republican donors are accordingly spending big in key Senate races.

In six of the seven tossup Senate races, Republican ad spending is far outstripping Democrats'. The biggest gap is in Texas ($141 million), but there are chasms also in Ohio (nearly $90 million), Maine (nearly $32 million) and Michigan ($33 million).