The key Republicans on immigration and gun violence — Sen. Marco Rubio of Florida and Toomey, respectively — have been in the chamber barely two years, and both hail from tea party roots, having won their party nominations by ousting establishment favorites.
"The more broad-based, the better," said Sen. Max Baucus, D-Mont., a 34-year veteran of the chamber and chairman of the Finance Committee.
But even though it appears beneficial to have more co-pilots involved in the takeoff, it remains to be seen whether that will complicate the landing for some of these measures.
Especially unpredictable, all sides agree, is the way ahead for the gun violence measures, because there are deep divides in both parties about how far to push in reining in gun rights.
Senate Republicans held a lunch that was intended to address both guns and immigration, including a highly anticipated briefing by Rubio, but senators said afterward that their gun debate took up so much time that they left the immigration discussion for another day.
Sen. Lindsey Graham, R-S.C. — who seems to be in the middle of just about everything lately — told reporters that he is working on crafting a Republican alternative that would include different provisions for gun trafficking, no expansion of background checks and other measures that gun-control advocates say would weaken the bill to a point where it would not be worthy of passage.
Other Republicans are gearing up for several weeks of debate and dozens of likely amendments, including many that would advance gun rights. GOP leaders have backed away from the position of its most junior senators, who have pushed to filibuster even the consideration of any gun legislation.
"There's going to be a fulsome debate. We welcome, notwithstanding some of the signals from some corners, we welcome a fulsome debate on this," Sen. John Cornyn, R-Tex., the No. 2 GOP leader, told reporters. "People are eager to have votes on amendments."