Even as outgoing Secretary of State Hillary Clinton was being grilled Wednesday about the U.S. response to the Sept. 11 terrorist attacks in Libya, political experts said the progressive icon still has the clearest route to the White House among Democratic hopefuls.

And despite national fatigue after a grinding election season, lawmakers appeared to have the party's next presidential nominee in mind as they questioned the witness Wednesday.

"You will be sorely missed, but I, for one, hope not for too long," Sen. Barbara Boxer, D-Calif., said to Clinton in a thinly veiled allusion to a possible White House run.

"I wish you the best in your future endeavors -- mostly, " quipped Rep. Steve Chabot, R-Ohio, prompting laughter from Clinton.

The bungled reaction to the deaths of four Americans, including Ambassador Christopher Stevens, at the U.S. consulate in Benghazi, Libya, represents a major blemish on the resume of the nation's top diplomat.

Yet, Clinton's approval ratings keep growing.

A new ABC News/Washington Post poll shows 67 percent of Americans view her favorably, an all-time high. By comparison, Vice President Biden, who has openly embraced a run for the White House, has a 48 percent approval rating in the same poll.

"I don't know if we've had a situation with a [possible presidential candidate] so well-known and so well-liked since Eisenhower," Democratic strategist Simon Rosenberg said. "Four years is far away, but I don't know that anybody challenges Hillary."

That is not to say the former first lady would have an easy path to the White House. She would trigger intense opposition among Republicans, many of whom continue to view her as a vestige of an ethically challenged administration. And, as documented in the 2008 primaries, Clinton makes a wide swath of Democratic primary voters uneasy.

The greatest unknown for Clinton is to what degree personal and health issues will affect a decision to run. Clinton would be 69 years old on Election Day, 2016. She was recently was admitted to a New York hospital for treatment of a blot clot, which formed after she suffered a concussion.

And some analysts cautioned against a coronation of Clinton as the successor to President Obama.

"Four years ago, people said the same thing: 'Who can take on Hillary,' " said Dennis Goldford, a political scientist at Drake University in Iowa, home to the first-in-the-nation caucuses. "She got into trouble last time by running a campaign of inevitability. The question is, who is the next Barack Obama?"

In addition to Biden, Maryland Gov. Martin O'Malley and New York Gov. Andrew Cuomo are considered possible Democratic candidates. Those alternatives don't enjoy the name recognition of the former first lady and at least publicly, have given no indication they would take on the Clinton political machine.

Some strategists said that Clinton's fate, like that of any future Democratic nominee for president, is inextricably linked to Obama's job performance during the next four years.

"If the country is in good shape four years from now, she'll be next to impossible to beat," conceded Republican strategist Ford O'Connell.

With a slip of the tongue, the White House unintentionally entered the handicapping contest for 2016. Obama spokesman Jay Carney accidentally referred to the secretary of state as "President Clinton," igniting a round of questions from reporters comparing the qualifications of Clinton and Biden.

Carney ultimately opined, "For the sake and sanity of all involved, it's worth taking a bit of a break from presidential election year politics."