Roll Call reports:
Maricopa County Sheriff Joe Arpaio led a field of potential Republican Senate candidates in Arizona with 21 percent in a poll of likely GOP primary voters last week.
Rep. Jeff Flake, who announced his candidacy for the seat of retiring Senate Minority Whip Jon Kyl (R-Ariz.) on Monday, finished second with 17 percent in the Summit Consulting Group survey. The auto-dial poll of 1,881 likely GOP primary voters was conducted Thursday and had a margin of error of 3 percentage points.
Former Rep. J.D. Hayworth took third, with 16.6 percent. He was unsuccessful in his primary challenge to Sen. John McCain last year.