No matter who makes it into the runoff, a two-person race will change the dynamics of the contests. For one, a two-person contest will allow candidates to draw clearer contrasts among a deeply conservative field. And if the field of candidates who donít make it through the runoff coalesce their supporters around the second-place finisher, that could spell trouble for Byrne, a gubernatorial candidate in 2010.
ďIf you canít hit above 45 percent when you are the most well-known guy, you just arenít going to make that up in the runoff,Ē Alabama Republican strategist Bob Kish said.
Not far away in Louisiana, the race to replace former Rep. Rodney Alexander, a Republican, features similar dynamics.
The Oct. 19 special primary also has a large field, and one of the 14 candidates in a wide-open primary field must receive the 50 percent necessary to avoid a runoff. State Sen. Neil Riser is the favorite, but itís nearly impossible for him to avoid the Nov. 16 runoff because of a crowded field.
And in Massachusetts, five Democrats are angling for the open 5th District seat on Oct. 15. This is the race to succeed Edward J. Markey, who won a Senate special election in June. Itís a wide-open contest among three candidates: state Sens. Katherine Clark and Karen Spilka and Middlesex County Sheriff Peter Koutoujian.
Democrats in that race are fighting for air time as a higher-profile Boston mayoral race takes place nearby. Democratic operatives say the race will come down to which candidate had the best ground game in what is expected to be an extremely low-turnout contest.
Finally, thereís the special election in New Jersey to succeed the late Sen. Frank R. Lautenberg, a Democrat, on Oct. 16. Booker is widely expected to defeat the GOP nominee, Steve Lonegan.
But this New Jersey race marks the first of three special elections that week, followed by House races in Louisiana and Massachusetts.
Former Sen. Scott Brown, R-Mass., candidate for U.S. Senate in New Hampshire, holds his hand over his heart during the singing of the national anthem as he waits to take the stage for his town hall campaign rally with Sen. John McCain at the Pinkerton Academy in Derry, N.H., on Monday, Aug. 18, 2014.