Senate Democrats need to pick up five seats to regain a majority.
The NRSC brought in $10.9 million for the first quarter of 2015.
The Democrat announced he will stay in the Senate.
The GOP senator donated to every member of his congressional delegation except Rep. Salmon.
It's the latest sign the free-market Tea Party group intends to be a major player this cycle.
State Republicans say Will Weatherford would have been a formidable challenger.
Sen. Ron Johnson (R-Wis.) is likely facing a difficult reelection battle in 2016.
Senate Conservatives Fund and FreedomWorks are nudging Rep. Ron DeSantis (R-Fla.) to run.
Ex-state Attorney General Catherine Cortez Masto (D) would be the first Latina in the Senate.
"No success in my life has ever come without a good fight," he said, announcing his bid.