From Jan. 1, 2017, through June 30 of this year, O’Rourke raised nearly $24 million. He more than doubled Cruz’ fundraising during the first six months of this year, and as of July 1 had more than $14 million in cash on hand to spend against Cruz. Comparatively, the senator banked only $9 million.

O’Rourke’s financial advantage appears to be the primary issue rattling team Cruz. It’s raised more alarm bells than public opinion polls showing a close race in the midterm election, with the incumbent leading by an average of 5.5 percentage points.

Indeed, Cruz’ big obstacle in the money chase is convincing Texas’ vast community of wealthy Republican donors that he needs help (the senator waltzed to victory in his general election six years ago.) They could give, or direct, tens of millions to the senator’s campaign and affiliated super PAC, “Texans Are.” But many are more worried about vulnerable GOP House members in suburban Austin, Dallas, and Houston, as well as a slew of endangered state legislative seats.