Representing as they might the in-power party, some presidential nominees will seek a disappearing act â€“ think Al Gore wishing Bill Clinton would vanish in 2000.
For others, it's a balancing act â€“ walking a political tightrope between past and present. Think George H.W. Bush embracing Ronald Reagan in 1988, while making it clear that he was his own man.
And in 2016: it's the spectacle of Hillary Clinton and her three-ball juggling act.
One ball in motion: Mrs. Clinton's embrace of the Obama Administration (including a big hug of the man himself) and the suggestion that she's a four-to-eight-year extension of his progressive outlook.
The second ball: that the real Hillary's a pragmatic, conciliatory moderate who doesn't intend to go down some of the same liberal rabbit holes as Obama. Note that, in her acceptance speech, she tried to extend an olive branch to gun-owners (more on that in a moment).
And the third ball: elect her and she'll bring Bernie Sanders' agenda to fruition: a living wage, higher taxes on the wealthy, putting big banks on notice.
In theory, Mrs. Clinton may be able to pull it off over the next 100-plus days. Yes, it's a "change" election. But it's also a "base election". If you take the time to read her Thursday evening remarks, it's clear that her campaign's calculation is to max-out on Democratic turnout (6% higher than Republicans in 2012) and, by ridiculing Donald Trump's temperament, hope to pick off enough disaffected independents and Republicans to get her over the top.
However, there are two big obstacles in Hillary's way.
First, there's the sincerity factor.
In 1992, Bill Clinton backed up the middle-ground talk by showing that he'd walked the walk as a southern governor. Carrying out executions in Arkansas and championing welfare reform did the job with skeptical voters (granted, it wasn't a ringing endorsement: Clinton backed into the White House with a mere 43% of the vote).
Hillary is a harder sell: she wants to placate the center, but it's not always a positive sales pitch.
Consider her approach to guns. Twenty reasons why she wants to tread delicately on the topic: Pennsylvania's 20 electoral votes.
Here's how Mrs. Clinton went after it in her acceptance speech:
"And if we're serious about keeping our country safe, we also can't afford to have a President who's in the pocket of the gun lobby. I'm not here to repeal the 2nd Amendment. I'm not here to take away your guns. I just don't want you to be shot by someone who shouldn't have a gun in the first place."
I italicized that middle part because of its inherit weakness. If the goal is to calm the Deer Hunter electorate, then try saying something more affirmative, such as: "I support the 2nd Amendment and your right to own a gun".
Instead, Mrs. Clinton tried to make a positive statement with a negative sentiment â€“ instead of "I love you", "I won't break your heart". That's not the stuff of wedding vows.
If you're the Trump campaign, this is your opening. Feed video of Nancy Pelosi's crack about "guns, gays and G0D" into battleground state, coupled with what President Obama had to say back in 2008 about some residents of the Keystone State (" . . . they cling to guns or religion or antipathy toward people who aren't like them or anti-immigrant sentiment or anti-trade sentiment as a way to explain their frustrations."
In addition to suggesting a cultural disrespect, why not suggest that this Clinton convention line â€“ "In my first 100 days, we will work with both parties to pass the biggest investment in new, good-paying jobs since World War II" â€“ would likely end up as another stimulus pork-barrel fiasco if her party gets control of Congress.
That takes us to Mrs. Clinton's second problem: as she tries to turn Trump into a cartoon figure, she has to deal with the fact that she's the long-suffering punch line to a long-running unflattering joke.
For years, Johnny Carson and Jay Leno entertained late-night audience with monologues. Their comedy was styled to mid-America. Unlike Letterman, Fallon, Colbert or Kimmel, it wasn't meant to be hip or cutting-edge, just what was in the news.
If you were a public official, cracking that monologue was a mixed blessing. If meant you were someone of note.
It also meant there was something about you â€“ a flaw, a deficiency, or a personality trait â€“ that made for easy lampooning.
Worst of all: done so often, the audience could anticipate where the joke was going.
Take George W. Bush. The punch-line: none-too-bright.
Bill Clinton? All monologue roads lead to sex.
And Hillary? A shady character and/or the oddness of her marriage.
How, then, does she unring the bell of being comedy-fodder for nearly a quarter of a century? A 55-minute speech in Philadelphia isn't enough. The too-cute language on guns and finding common ground in Washington doesn't come across as convincing â€“ not with an agenda that's largely dead on arrival with a Republican majority in either the U.S. House or Senate.