The marquee clash between GOP Sen. Ted Cruz and Democratic Rep. Beto O'Rourke has clearly tightened, and Democrats are (perhaps overly) excited about the potential for a historic breakthrough in the Lone Star State. It's possible that O'Rourke could fall a few points short of statewide victory in November, but his strong standing in suburban districts has begun to concern down-ballot Republicans.

There's scant evidence that O'Rourke's 254-county tour has moved the needle much in rural Texas, where Democrats hope would-be Cruz voters will simply stay home. But it's a different story in Texas's upscale suburbs: private polling on both sides now shows O'Rourke substantially outperforming Hillary Clinton's percentages in multiple highly college-educated districts near Houston and Dallas.

That's serious cause for concern for Houston GOP Rep. John Culberson (TX-07) and Dallas GOP Rep. Pete Sessions (TX-32), who sit in seats Clinton carried and are already in the Toss Up column. But it also should be a wake up call for several other Republicans who haven't had a competitive race before but sit in upscale suburban seats President Trump carried

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