AUSTIN, Texas -- While a Democrat hasn't won statewide office in more than two decades, Congressman Beto O'Rourke (D-El Paso) is packing town halls and out-raising the incumbent Sen. Ted Cruz (R-TX).

Even Cruz is warning Texas Republicans about a possible rocky ride in November and both men were campaigning over the past few days.

"I think the energy is positive, I think it's a good thing for Texas, and we'll see it at the ballot box March 6," O'Rourke said at a campaign stop in San Marcos Monday.

The pre-primary energy is turning into campaign cash. O'Rourke outraised Cruz in the last few months of 2017, and boasts of not taking political action committee money.

While Cruz still has more cash-on-hand, the incumbent Republican is warning his wing not to take anything for granted.

"There is an incredible volatility in politics right now," Cruz said.

Speaking at a GOP fundraiser last week, Cruz acknowledged the Democratic momentum.

"They will crawl over broken glass in November to vote. 2018 is entirely a turnout election," Cruz said.

Congressman O'Rourke is banking on that high turnout.

"It's on us to run a campaign that ignores no one, leaves no one behind, makes sure that everyone is important, and I'm convinced when we do that, visiting all 254 counties, we're going to give everyone in Texas a reason to vote," O'Rourke said.

Recent polling on the race doesn't paint the most precise picture. One released last month by the Democratic group Public Policy Polling found O'Rourke to be trailing Cruz by just 8 points. However, internal polling by the Cruz campaign showed the senator up by 18 points.