Three years out from Election Day 2016, there is already a lot of talk about whose stock is rising in the presidential race. For Republicans, the response is almost automatic: Rand Paul and Ted Cruz, two stand-out freshmen senators who both have the support of the Tea Party.

“Either one of them would be an incredible leader,” said Tea Party Express Chairwoman Amy Kremer. “They’re both Team America, and that’s what team I’m on and this movement’s on.”

Paul, of Kentucky, and Cruz, of Texas, have stirred passionate support among conservatives, many of whom came to know the two lawmakers when each was waging a filibuster (a long speech for Cruz, technically), taking control of a chamber to which Paul has belonged since 2011 and Cruz joined in January.

That both lawmakers have taken positions at odds with their Republican leadership — and have in so doing paid unwavering attention to issues important to their conservative supporters — has only increased admiration for them among their core constituencies.

But for their similarities, Republican lawmakers and aides have begun to take note of a stylistic and legislative gap that is widening between the two potential presidential contenders.

The distinctions were in high relief this week, particularly for Cruz, who positioned himself at the forefront of the debate over a doomed measure to defund the Affordable Care Act as part of a must-pass budget bill.

Both Cruz and Paul want to abolish "Obamacare." But Cruz took that message directly and bluntly to conservatives, advocacy groups and campaign contributors with a dramatic 21-hour speech on the Senate floor, despite the clear legislative reality that he could not defund the health care law.

That strategy, Cruz told the Washington Examiner, was by design.

"There are too many politicians, in my opinion, in both parties, who are not listening to the American people," Cruz said. "The most significant thing that Sen. (Mike) Lee and I are trying to do is help change the culture in Washington so that our elected officials listen to the people."

While he played well with people outside the Beltway, Cruz's tack has left many of his Republican colleagues incensed. After a heated exchange with Cruz on the Senate floor Thursday, Sen. Bob Corker, R-Tenn., was too flustered to talk on the record about Cruz.

Paul strikes a very different tone, even in his most contrarian moments. He tends to work collegially and within Senate traditions, earning respect from other senators despite their occasional, but fundamental, policy disagreements.

"Unlike Cruz, Paul is not only playing the outside game, but he seems to understand the importance of working with his Senate colleagues — not blowing them up," said a Senate Republican aide.

This differences between Cruz and Paul is due in part to Paul caring more about legislative outcomes and Cruz catering more to political ones, at least so far. But political ideology also factors in. Paul appeals to a rising libertarian strain of the Republican Party, while Cruz draws much of his support from conservative ideologues.

Sen. Lindsey Graham, R-S.C., has worked with Paul closely on legislation, and has noticed Paul's ability to draw support from both sides of the aisle, uniting libertarians and liberals, even while tackling politically treacherous issues.

"He’s not shy at all about taking on political challenges, third rails," Graham said.

Cruz is newer to the Senate, Graham noted, and in rising fast has also acted to reap immediate political rewards.

"Obviously he’s got passion, which is a good thing," Graham said, "but at the end of the day it’s about results."