WASHINGTON -- Hillary Clinton already has a running mate: Barack Obama.

This makes Republicans happy, because there's no easier line of attack (or mechanism for fundraising) than saying a Clinton victory would amount to a continuation of the current presidency. Nearly every communication from the Republican National Committee about Clinton's candidacy hammers on that point. “America deserves better than a third term of the Obama-Clinton policies,” said RNC Chairman Reince Priebus in a recent statement about GOP fundraising.

Any presidential candidate who belongs to the same party as the current occupant of the Oval Office has to deal with that administration's record and that president's popularity (or lack thereof). And Clinton, as Obama's first secretary of state, is linked to him even more tightly than a Democratic governor or senator would be.

“At some point you have to embrace the charge and run as a proud Democrat,” Jim Manley, a Democratic strategist, said. “You can’t run away from it, not in this day and age. The ads are coming, you’ve got to acknowledge it, figure out ways to try to highlight differences where appropriate, and you’ve got to understand there is no denying that you’re going to suffer these kinds of attacks.”

Still, Clinton needs to separate herself from Obama -- partly because his administration is so polarizing, and partly because any presidential candidate has to define herself as her own person. Even George H. W. Bush, following the immensely popular Ronald Reagan, positioned himself as a "kinder, gentler" version of the man he'd served as veep for eight years.

But Clinton must be careful. She's relying on the same coalition of supporters that put Obama into the White House and kept him there: younger voters, women, Latinos and African-Americans. (Republicans can count on winning a majority of white men.) Clinton needs those groups to be not just loyal but enthusiastic. After all, Mitt Romney's team thought their candidate would win in 2012 partly because they didn't expect such a high percentage of Obama's supporters to show up. If Clinton moves too far away from Obama -- especially if she appears to disrespect him -- his base is unlikely to turn out in such numbers. 

“There is no entitlement to that coalition,” a Democratic strategist said. “The fact is, Hillary Clinton is going to need to be similarly seen as a credible advocate for those constituents.”

Being tied to Obama isn't as bad as it might have been. The president’s approval numbers are trending upward, and the economic recovery is strong, if uneven. Strategists agree that Clinton will likely benefit from associating herself with the president’s economic policies and his overall domestic record. She has praised the Affordable Care Act, though saying it could be improved. (If the Supreme Court overturns the law, she'll need to present an alternative, which would be a politically fraught challenge, since her attempt at health care reform during her husband's administration, dubbed Hillarycare, famously failed.)

But with the world in turmoil (e.g., the rise of the Islamic State group, President Putin's belligerence in Russia, etc.), she will probably want to distance herself from Obama's foreign policy. She can't repudiate the administration completely since she was, after all, secretary of state for four years. But Clinton has long been seen as more hawkish than Obama, and there are areas on which she can credibly claim to differ with him. For example, during the 2008 campaign she mocked his stated willingness to negotiate with Iran, a stance that might be popular now. Asked recently about the fight against ISIS, Clinton was reserved. “I think a lot of the right moves are being made, but this is a very complicated and long-term problem. This is a long-term struggle,” she said.

As the campaign goes on, Clinton will have to decide whether to deploy Obama as a surrogate. She may not want him onstage with her, because a joint appearance could validate the idea that she'd just be Obama's third term. But there are ways he could help that don’t involve giving a stump speech. The president remains a fundraising draw. His campaign shifted into nonprofit-advocacy mode after the 2012 campaign with the creation of Organizing for America, which could provide an extensive campaign infrastructure. Many of Obama’s closest aides are already set to work for Clinton, lending her their deep knowledge of the electoral process.

During the 2014 midterm campaign season, Democrats largely kept the president locked in the White House. His job approval rating was at 40 percent the week of the election. Few candidates wanted him to stump for them, and he was mostly relegated to fundraising appearances in states that didn’t have competitive races. But after taking a shellacking in the Senate and the House, Democrats wondered if that had been the best decision. 

“Those who think she’s going to run away from him, we saw in the midterms that’s not a good strategy, but secondly, I don’t think that’s her inclination,” David Axelrod, a top Obama adviser, told CBS News.

Clinton is intimately familiar with what happens when a candidate abandons the occupant of the White House. In 2000, Al Gore very publicly distanced himself from President Bill Clinton. Bill Clinton was popular at the time, with a 63 percent job approval rating on Election Day. He had a 70 percent approval rating among independents. But Gore was fearful that the Monica Lewinsky scandal would tarnish his run, and perhaps also was tired of living in Bill Clinton's large shadow.

President Clinton complained that Gore didn't call on him to campaign and failed to consult him on strategy. The two men ultimately blamed each other for Gore's loss, according to Marjorie Williams in "The Woman at the Washington Zoo."  

“It was a strategic blunder of the first order," a Democratic strategist said. "I think President Obama will be a very valuable surrogate for Secretary Clinton if she asks him to be.” 

But there is also a recent example of what happens to a candidate when the president of the same party is not so popular. President George W. Bush's approval rating was 28 percent on Election Day 2008. Not once did U.S. Sen. John McCain, R-Ariz., invite Bush to campaign with him, and the former president took issue with it.

“I understood he had to establish his independence,” Bush wrote in his memoir. “I thought it looked defensive for John to distance himself from me. I was confident I could have helped him make his case. But the decision was his. I was disappointed I couldn’t do more to help him.”

A twice-elected incumbent, of course, assumes he'd be a help. But the candidate who hopes to replace him doesn't necessarily see it the same way. Hillary Clinton will have to decide how much space she should put between herself and the current president, in order to be the next one.