The Pennsylvania Republican Party endorsed businessman Steve Welch to take on Sen. Bob Casey (D-Pa.) over the weekend, a major boost in a crowded GOP field.

Welch, a wealthy businessman who has the ability to self-fund, was backed by 57 percent of state party officials, while the second-place candidate was at just 16 percent.

Welch's advantage came partly from the strong backing of Pennsylvania Gov. Tom Corbett (R).

Some party officials have tried to pressure Tim Burns, who lost two races against Rep. Mark Critz (D-Pa.), to drop out of the Senate race and take a third shot for Congress in a district where Critz and Rep. Jason Altmire (D-Pa.) are running. But Burns said after the vote that he's staying in the race.

Some Tea Party supporters are unhappy with the process, however.

Whichever Republican winds up with the nomination will have an uphill battle: Casey has been strong in polls. If the Republican Party can unite behind one candidate, they will have a better shot at giving Casey a tough challenge.