The Republican primary in Arizona's 1st congressional district was still too close to call Wednesday morning. That should make Republicans nervous.

State House Speaker Andy Tobin was clinging to a 291-vote lead over rancher Gary Kiehne, according to results compiled by the Associated Press. State Rep. Adam Kwasman was on pace to finish third. The totals come from 325 out of the 327 precincts in the district, according to the AP's tally.

The winner will face Rep. Ann Kirkpatrick (D), who is vulnerable to a Republican challenge in November. But Kirkpatrick's fate could be heavily determined by which Republican wins the primary. If it's Tobin, it's bad news for Kirkpatrick. He's the establishment candidate viewed by most strategists as most electable.

If's it's Kiehne, it's great news for Kirkpatrick. He has a tendency to stoke controversy, which could alienate moderate voters. For example, Kiehne once blamed "99 percent" of mass shootings on Democrats. He later apologized.