President Obama's veto threat against a proposed deal between top Senate Democrats and House Republicans has stalled progress on renewing an expired package of tax breaks. Jacquelyn Martin/AP hide caption

itoggle caption Jacquelyn Martin/AP

Former Florida Gov. Jeb Bush addresses an education conference Thursday sponsored by the Foundation for Excellence in Education, a nonprofit he created as he left office. Susan Walsh/AP hide caption

itoggle caption Susan Walsh/AP

GOP Rep. Bill Cassidy and Democratic Sen. Mary Landrieu face off in a Dec. 6 Senate runoff. Both are pushing for legislation approving the remaining leg of the Keystone XL pipeline between Alberta, Canada, and Steele City, Neb. Gerald Herbert/AP hide caption

itoggle caption Gerald Herbert/AP

It's a long shot, but there's a scenario where control of the Senate might not be known until Jan. 6 — three days after the start of the next Congress. That's when Republican David Perdue and Democrat Michelle Nunn will face each other in a Georgia runoff if one of them fails to win 50 percent on Tuesday. David Tulis/AP hide caption

itoggle caption David Tulis/AP