Would a presidential run by Joe Biden aim to knock Hillary Clinton out or serve as a standby?

Reporting from Washington —  As Vice President Joe Biden continues to publicly ponder whether to enter the presidential race, a key question has emerged: If he runs, would he try to push Hillary Rodham Clinton aside or, simply and more gently, stand as a possible replacement?

In the space of 36 hours this week, Biden offered a glimpse of both strategies.

At stops in South Florida and Atlanta, he offered domestic and foreign policy arguments for why he should be president. The appearances allowed him to boost his candidacy and contrast himself with his chief potential opponent without ever mentioning her by name or spending a dime from his nonexistent campaign war chest.

At a community college in Florida, he played a favorite political character — Middle Class Joe — as he promoted the administration’s economic policies.

“Being in the middle class is not a reflection of your salary. It’s a value set,” he said.

Later, in Atlanta, he offered a comprehensive analysis of the foreign policy challenges and opportunities the U.S. faces, allowing him to tout his national security credentials — again, in an unstated contrast with Clinton.

But at an Atlanta synagogue Thursday night, when asked whether he might enter the presidential race, the answer suggested not a man preparing to wage an aggressive campaign, but one who leans toward waiting things out as he and his family wrestle with the wrenching loss of his oldest son, Beau.

“There’s no way to put a timetable on that,” he said. “If I can reach that conclusion that we can do it in a fashion that would still make it viable, I would not hesitate to do it,” he said. But, he added, “I have to be honest with you and everyone who’s come to me: I can’t look you straight in the eye and say now I know I can do that.”

Biden’s aides see a genuine interest among voters in the possibility of his running. They bristle at the conventional wisdom that Biden could not go toe-to-toe with Clinton if that’s what he chooses to do. The vice president would have an opportunity to make up for lost time with performances in debates, they believe, and could enter the race with the advantages that come with his office and a political environment that seems to match his personal brand as an authentic, plain-spoken warrior for the middle class.

They’re also eyeing the incessant questions over Clinton’s private email server.

It would be “malpractice not to,” as one person close to the vice president’s deliberations put it.

But people close to Biden insist that running a negative campaign, the sort that would be needed to actually knock Clinton out of the race, is not in Biden’s character. They point to 2008 to show how reluctant he was to do that kind of attack strategy, both in the primary and especially after he was selected as Obama’s running mate. Vice presidential candidates are often put in the role of attack dog, but Biden would regularly recall his friendship with the Republican presidential candidate, Sen. John McCain of Arizona, and praise his heroism before wading into policy critiques.

To the extent there’s been a campaign blueprint waiting to be executed, it calls for Biden to run a positive, forward-looking campaign based on his own qualifications and vision for the country. It’s something of an homage to the “happy warrior” approach of one of his political mentors, Hubert H. Humphrey, another former senator who ran for president as a sitting vice president in 1968.

The type of positive campaign that Biden prefers, however, could fit the voters’ mood and act as an implicit response to Clinton’s vulnerabilities. His presence as a potential candidate has already raised unflattering comparisons between the two and drawn attention to polling that shows how differently the two Democrats are perceived by the public.

A recent Quinnipiac University poll showed 48% of Americans had a favorable view of Biden, while 39% viewed him negatively. Clinton’s numbers were nearly the opposite — 39% viewed her favorably, 51% negatively. Importantly, he also held an advantage among registered Democrats, with a net favorable rating 12 points higher than Clinton’s.

Of course, as Clinton’s aides know all too well, a politician’s public image almost always goes down once he or she becomes involved in an actual campaign.

Biden also has a knack for making indirect, and not entire subtle, comparisons between himself and Clinton.

“I’ve traveled, as of today, 992,894 miles for the president. I’ve met with virtually every major leader in the world,” he told his audience in Florida. “I know these guys. I know them better than anybody in the administration,” he said. Clinton has often noted her extensive travels as secretary of State — but her mileage log for four years is some 36,000 fewer than Biden’s in nearly seven.

In a 2013 speech in Iowa, Biden conspicuously singled out John F. Kerry as “one of the best secretaries of state so far in the history of the United States of America,” though he’d been in the post just months at the time.

Clinton, in an interview Friday with NBC’s Andrea Mitchell, declined to identify any policy differences between herself and Biden, calling him “my friend,” while noting how he was “struggling” with the decision on whether to run.

“If he continues as vice president, he will continue to serve with great distinction. If he gets into this race, there’ll be plenty of time to get into the debate and the back and forth,” she said.

In some corners of the party, there’s pressure for Biden to make a quick decision, but the week’s events show why people close to the vice president believe he has time to wait things out. As the vice president himself said a year ago in a television interview: “Everything I think I would have to do to be a viable candidate is the same exact thing I should be doing to be the best vice president I could possibly be.”

The issues Biden spoke about in the past week — foreign policy and the plight of the middle class — would be central to his candidacy. The balance of power on the Supreme Court also would be a major issue for the former chairman of the Senate Judiciary Committee.

For their part, Clinton’s top campaign advisors say they have no plans to change strategy if Biden were to enter the Democratic presidential race, even as they concede he would “shake up the dynamic quite a bit.”

“He is a sitting vice president. He is certainly going to be a commanding presence in the race,” campaign manager Robby Mook told reporters on a conference call Thursday. “But our strategy will remain the same, to fight for every single vote.”

Follow @mikememoli for more news out of Washington.