It's an uphill battle for President Obama to get his yet-to-be-determined Supreme Court nominee through a Republican-controlled Senate.

But because he is empowered to choose whom he wants to replace Justice Antonin Scalia, who died Saturday, Obama may have the upper hand in the political confirmation fight that follows — and, perhaps most crucially, any electoral fallout from that battle.

Senate Majority Leader Mitch McConnell (R-Ky.) said he won't consider any nominee so late in Obama's presidency. Knowing that, Obama has a few confirmation paths to choose. He can try to pick a liberal firebrand who rallies Democrats, a moderate Republican who puts Senate Republicans in an awkward spot to oppose, or someone in between.

Almost all such picks could make life difficult for Senate Republicans — especially in the 24 GOP seats that are up for reelection and for the eight or so vulnerable Republicans seeking another term.

Here are five potential picks that could make Republicans squirm the most — and why:

1. Attorney General Loretta E. Lynch

U.S. Attorney General Loretta E. Lynch (Nikki Kahn/The Washington Post)

The New York Times notes that the last white man a Democratic president nominated to the Supreme Court was Stephen G. Breyer in 1994. So it's more likely than not that Obama will take this last opportunity to shape the nation's court for a generation and nominate a candidate from a diverse background. At the top of most insiders' lists is Lynch, a Democrat who was confirmed by the Senate to run the Justice Department in April and who would be the first black woman to serve on the court.

Why Republicans should fear her nomination: Lynch, quite simply, is a double whammy of diversity and talent. Refusing to even consider her, as Senate leaders say they are inclined to do for Obama's eventual nominee, could come across as off-key as well as blatantly political. Obama also can make the case that the Senate already vetted Lynch and that 10 Republicans voted for her confirmation.

Plus, the thwarting of a potentially groundbreaking nominee such as Lynch can help motivate the Democratic base, making life harder for vulnerable Senate Republican incumbents who are up for reelection in swing states.

But: Here we run straight into the intractable politics of this vacancy. If Obama nominates Lynch, she may have as good a shot as anyone to get a hearing and possibly even a vote in the Senate. But she would probably need all 46 Democrats and at least 14 Republicans to vote for her. And the GOP base will fight tooth and nail against anything that will shift the court to the left, as basically any Obama-nominated replacement for Scalia would.

2. Judge Sri Srinivasan

Then-U.S. Deputy Solicitor General Sri Srinivasan. United States Department of Justice/Reuters

He's young (48). Like Lynch, his confirmation would be historic (as he'd be the first South Asian American on the Supreme Court). Like Lynch, the D.C. Circuit Court of Appeals judge was already vetted by the Senate (and confirmed 97-0 in 2013).

And, as Elena Schor of Politico noted, his record suggests he's no tree-hugging liberal. He has defended giant corporations, such as ExxonMobil, against human rights charges, and their leaders, such as former Enron chief executive Jeff Skilling, in appealing fraud and conspiracy convictions. He clerked for Justice Sandra Day O'Connor, who was a Ronald Reagan appointee, and he was an assistant solicitor general under President George W. Bush.

Why Republicans should fear his nomination: Saying no to a compelling, moderate choice like Srinivasan risks making Senate Republicans look as if they're saying no simply to oppose Obama instead of considering the best candidate for the job. Again, there is the prospect of rejecting a highly qualified minority candidate.

But: It's an open question of whether someone as talented as Srinivasan would want to jump head-first into the political circus with absolutely no guarantee he would ever get the job — or even a chance to pitch himself for it in a Senate hearing. This is a guy, after all, who seems a good bet to get on the Supreme Court eventually. And a botched nomination hearing could hurt his stock.

3. Sen. Elizabeth Warren (D-Mass.)

Massachusetts Sen. Elizabeth Warren (Cheryl Evans/The Arizona Republic via AP)

Obama could calculate that his pick has virtually no chance of making it through the Senate and instead aim for an overtly political pick — someone he thinks will have the best chance of motivating his party to put a Democrat in the White House and Democrats in control of the Senate.

Why Republicans should fear her nomination: Talk about rallying the base. Few fit that bill as neatly as Warren, the senator from Massachusetts who has become one of the left's leading voices for economic populism and deserves credit for helping shape the leftward nature of the party's current nomination for president.

But: Insiders think it's unlikely Obama would nominate a sitting Democratic senator, no matter the potential political benefits. And Obama and Warren aren't necessarily buddy-buddy. Warren is known to publicly criticize the president on matters ranging from allegedly cuddling up to Wall Street to supporting free trade.

4. Sen. Orrin Hatch of Utah

Sen. Orrin Hatch, R-Utah (AP Photo/Rick Bowmer, File)

Staying in the Senate for a moment, another name that could put Republicans in a quandary — for an entirely different reason — is one of their own, the senior senator from Utah. The current chairman of the Senate Finance Committee is also Republicans' well-respected party elder; he's the most senior Republican senator and no slouch when it comes to conservative principles. But he's also moderate enough that he found himself targeted by more-conservative elements of the GOP in his last reelection bid.

Why Republicans should fear his nomination:  It's a long-shot, but the thinking here goes that putting Republicans in a position to have to block one of their own would surely expose their unreasonable intransigence that Democrats claim has stymied the country for so long. And Hatch says he'd take the nomination and run with it.

"I'd be up for the job," Hatch told NPR on Monday.

But: Hatch turns 82 next month, which is a major disqualifier for a president with a ninth-inning chance to make such a lasting impression on the country with this vacancy. And Hatch, in that same NPR interview, joked he'd have to watch his back once on the court: "I'm not sure I would want to be appointed and to have all the Democrats praying that I’d die real soon after."

5. Nevada Gov. Brian Sandoval

Nevada Gov. Brian Sandoval (AP Photo/Kevin Clifford, File)

Outside the Beltway, there's one name that could really make things awkward for Republicans — mostly because he's such a qualified candidate. Like many of the other picks on this list, Sandoval, a Republican, has a dynamic background. He is a Hispanic representing an increasingly important and diverse swing state, he's a former federal judge, and he's moderate enough for Democrats to potentially stomach. (Sandoval supports abortion rights and comprehensive immigration reform, took a moderate stance on whether to allow Syrian refugees into Nevada, and has not fought the Supreme Court's legalization of same-sex marriage.)

Why Republicans should fear his nomination: The governor is such a consensus-building candidate that, by picking him, Obama would be extending an olive branch that Republicans could look foolish in batting away.

But: It's considered bad form for presidents and senators to have litmus tests when nominating or confirming someone to a lifetime appointment on the court, but there's no getting away from the fact that Sandoval supports abortion rights, and that's a nonstarter for huge and vocal parts of the GOP base. (It's one thing to have a pro-abortion-rights GOP governor; it's another to have him sitting on the court responsible for Roe v. Wade.) It would be difficult to near-impossible to imagine 14 Senate Republicans voting to the highest court someone who opposes this most basic conservative principle. And it's likely that some Senate Democrats would balk at a guy who is pretty conservative on many other issues.