The midterm-election horserace is into its final furlong — and that means most of the attention of the political world is focused, understandably, on who’s up and who’s down; who will win and who will lose.

But if Republicans succeed in their quest to secure a Senate majority on Tuesday, what will really change on Capitol Hill?

The answer is “plenty” – both in terms of policy and politics.

Here are five areas to watch.

1. Will President Obama’s big achievements be hollowed out?

Republicans say that if they gain control of Congress they will start chipping away at two of the Obama administration’s biggest victories: financial reform and healthcare.

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The GOP could well decide against attempting another full repeal of the Affordable Care Act. But its members would probably try to eliminate the much-discussed medical device tax. They might also look at nixing the employer mandate.

The Dodd-Frank financial law is high on the hitlist of GOP lawmakers. They want to ease capital requirements for large insurance companies, create both a board of directors and a new inspector-general position for the Consumer Financial Protection Bureau, and streamline a process for banks deemed too big to fail.

More generally, Republicans have made it clear that Obama’s regulatory agenda is a prime target.

With control over the budget and appropriations process, Republicans could cut off funding that is needed to implement or enforce regulations — including the EPA’s carbon-pollution standards for power plants, which form a big piece of the president's climate agenda.

The GOP will also probably ramp up efforts to push through the Keystone XL pipeline and expand natural-gas exports.

2. Senate confirmations: The battlefield tilts

A GOP-controlled Senate will make it even tougher for Obama to confirm nominees, a process that hasn’t exactly been plain sailing even with Democrats in charge.

Although Supreme Court Justice Ruth Bader Ginsburg has said she is staying put, it remains plausible that Obama could be faced with a third chance to put his stamp on the court. Republicans would find it much easier to block his choice if they held the majority in the Senate.

Obama will also nominate a replacement for retiring Attorney General Eric Holder Eric Himpton HolderThe Hill's Campaign Report: Trump's rally risk | Biden ramps up legal team | Biden hits Trump over climate policy Biden campaign forming 'special litigation' team ahead of possible voting battle Pompeo, Engel poised for battle in contempt proceedings MORE, and the confirmation process will likely be fraught whomever he chooses.

Obama also isn’t like to face any shortage of executive branch, ambassador and federal judicial nominations in his final two years in office. They will all need Senate confirmation.

3. Obama to stock up on veto pens

Obama has had to pick up his veto pen on just two occasions since he took office in 2009, largely because Democrats have controlled at least one chamber of Congress throughout that time.

He will need to check he has a plentiful supply of ink if Republicans take the Senate majority. He can expect to spend his final two years using his veto to protect earlier legislative victories, rather than seriously attempting to rack up new ones.

There is some chance of bipartisan progress on issue such as immigration reform and global trade deals. But it also seems likely that Obama will need to rely on executive action if he wants to pursue many of his priorities.

4. More Benghazi, more anti-ISIS action

If Republicans take over the Senate, Sen. John McCain John Sidney McCainMomentum growing among Republicans for Supreme Court vote before Election Day McConnell urges GOP senators to 'keep your powder dry' on Supreme Court vacancy McSally says current Senate should vote on Trump nominee MORE (R-Ariz.) will take the gavel at the Armed Services Committee. He is almost certain to turn the spotlight back onto the Obama administration’s missteps in Benghazi — especially the ones that Republicans say were committed by Hillary Clinton Hillary Diane Rodham ClintonBiden leads Trump by 36 points nationally among Latinos: poll Democratic super PAC to hit Trump in battleground states over coronavirus deaths Battle lines drawn on precedent in Supreme Court fight MORE, who was secretary of State at the time.

Congressional Republican make little secret of the fact that they believe the controversy could hurt Clinton’s chances of winning the White House in 2016. Senate control would ensure they could keep it high up on the news agenda.

Republicans also are likely to push for a more aggressive U.S. response to the militants of the Islamic State in Iraq and Syria, or ISIS. They have long argued that the Obama administration isn’t being aggressive enough in that fight.

While their push probably won’t come in the form of asking for more U.S. troops in Iraq and Syria, Republicans insist that the United States ought to do more to quell terrorist threats in the region.

Republicans are faced also with a slew of expiring bills but none more important to national security than an NSA surveillance reauthorization.

It will be up to the GOP to push a bill across the finish line, just as 2016 presidential contenders ramp up their campaigns. Many national security experts have argued that letting the current law expire would be disastrous.

5. 2016: The future starts now

Whoever wins and loses on Tuesday night, much of the political world will turn its focus to 2016 as soon as dawn breaks on Wednesday.

If the GOP controls both chambers in the new Congress, its leaders will take every step over the following two years with an acute appreciation of how their moves might affect the 2016 race for the White House.

They will have to walk a fine line: They will want to make Democrats take tough votes while also helping those within their own ranks who might seek the Oval Office. GOP Sens. Rand Paul Randal (Rand) Howard PaulSecond GOP senator to quarantine after exposure to coronavirus GOP senator to quarantine after coronavirus exposure The Hill's Morning Report - Sponsored by National Industries for the Blind - Trump seeks to flip 'Rage' narrative; Dems block COVID-19 bill MORE (Ky.), Ted Cruz Rafael (Ted) Edward CruzMurkowski: Supreme Court nominee should not be taken up before election Battle lines drawn on precedent in Supreme Court fight Sunday shows - Ruth Bader Ginsburg's death dominates MORE (Texas), Marco Rubio Marco Antonio RubioSunday shows preview: Justice Ginsburg dies, sparking partisan battle over vacancy before election Florida senators pushing to keep Daylight Savings Time during pandemic Hillicon Valley: DOJ indicts Chinese, Malaysian hackers accused of targeting over 100 organizations | GOP senators raise concerns over Oracle-TikTok deal | QAnon awareness jumps in new poll MORE (Fla.) and Rob Portman Robert (Rob) Jones PortmanMcConnell locks down key GOP votes in Supreme Court fight Romney undecided on authorizing subpoenas for GOP Obama-era probes Congress needs to prioritize government digital service delivery MORE (Ohio) have all had their names bandied about as 2016 hopefuls.

There will also be the concerns of those senators seeking reelection in 2016 to consider. Some centrist Republicans may seek to forge new relationships with Democrats in order to advance legislation they deem important to their reelection hopes.

Julian Hattem, Kristina Wong, Laura Barron-Lopez, Bernie Becker, Ben Goad and Mike Lillis contributed.