Rep. Kyrsten Sinema, a freshman Democrat in one of Arizona’s most competitive districts, will get her first GOP challenger on Sunday.

Retired Air Force Lt. Col. Wendy Rogers emailed supporters earlier this week announcing a St. Patrick’s Day campaign kickoff in Phoenix.

“She will become Arizona’s first Republican congresswoman ever elected,” the invitation read. “Climb aboard to become a part of Arizona history in the making!”

Rogers ran unsuccessfully for the GOP nod in the same district in 2012, along with Paradise Valley Mayor Vernon Parker and businessman Martin Sepulveda. Parker won the nomination but lost to Sinema by 4 points.

The GOP field is expected to be crowded in 2014. In December, Sepulveda  indicated to CQ Roll Call he was seriously considering a run for Arizona’s 9th District. Republicans also mentioned former Rep. Ben Quayle, R-Ariz., for the seat a few weeks ago — although sources said his candidacy has become increasingly less likely more recently.

This is a Tossup district, and Republicans plan to target it. The Democratic Congressional Campaign Committee already named Sinema to its “Frontline” program for vulnerable incumbents.

But operatives of both parties caution that Sinema is on better footing today than last cycle. National GOP operatives celebrated her nomination last August, declaring her to be one of the weakest candidates on the Democratic map. This time around, Arizona Republican sources desperately want a strong candidate to get organized early in order to effectively challenge her.