Rep. Jeff Flake (R-Ariz.) used his announcement for a Senate bid to proclaimed runaway government spending is "a clear and present danger" to the future of the nation.
"We have got to solve this problem," Flake said of the growing federal budget deficit on Monday, according to KPHO-TV in Phoenix. "I'm heading to Washington today to confront the $1.5 trillion deficit and $14 trillion debt."
Flake also put immigration near the top of his issue list, noting the need to focus first on border security.
With his quick entry into the race, Flake takes on the frontrunner mantle on the Republican side, despite the potential for a crowded primary.
As soon as Kyl announced his decision to retire last week, Republican insiders pegged Flake as the man to beat for the nomination and the conservative Club for Growth quickly endorsed him Monday morning, as expected. The Club publicly urged him to run last week.
"Jeff Flake is a proven, tireless champion for economic freedom, and Club for Growth PAC will do everything it can in the Republican primary and general election to help him win this race," Club for Growth President Chris Chocola said in a statement Monday.
The Club for Growth promotes conservative fiscal policies and Flake is known for attacking earmarks and unnecessary spending.
In his endorsement, Chocola noted Flake's efforts in opposing "the worst policies of the Bush Administration and of the previous Republican Congress, like earmarks, bailouts, and the prescription drug entitlement."
Rep. Trent Franks (R-Ariz.) and former Rep. J.D. Hayworth (R-Ariz.) are among the Republicans who are also considering bids for the seat.
-- This post was updated at 11:38 a.m.