Many found Warner, a likely contender for the 2008 Democratic presidential nomination, fresh and forceful. Others thought his speech not quite ready for prime time.
"It was a little too corporate - not enough passion," said one New Hampshire Democratic activist who asked that his name not be used in criticizing a politician who might be his party's choice for president. "I'll bet you anything that in six months, this isn't his speech."
The good news for Warner is that he has plenty of free time to hone his stump speech - and to focus on every other aspect of a possible presidential campaign.
Warner, who stepped down as Virginia's governor in January, is part of an unusually large number of politicians - in both parties - who might seek the 2008 presidential nominations while out of office.
The group could include as many as six Democrats and five Republicans.
This prospect is sure to revive an old debate among political professionals: Does the race for the presidency favor candidates who hold an elected office or those who don't? Most political strategists would answer the latter, but history points toward the former.
Among Republicans, potential 2008 contenders include Senate Majority Leader Bill Frist of Tennessee, Massachusetts Gov. Mitt Romney and New York Gov. George E. Pataki - each of whom is leaving his post after November's election.
Former House Speaker Newt Gingrich of Georgia, who resigned from Congress after the GOP suffered unexpected congressional losses in the 1998 election, and former New York City Mayor Rudolph W. Giuliani, who left office in 2001, are also possible candidates.
Among Democrats, Warner (who in New Hampshire jokingly described himself as "unemployed") and former Sen. John Edwards of North Carolina, the party's 2004 vice presidential nominee, seem virtually certain to run.
Iowa Gov. Tom Vilsack, who is not seeking re-election this year, is viewed as a likely presidential contender, and former Senate Majority Leader Tom Daschle of South Dakota has kept his name in the mix.
Retired Gen. Wesley K. Clark, who sought the nomination in 2004, and former Vice President Al Gore, the party's nominee in 2000, continue to generate buzz among activists.
In each party, the number of 2008 presidential aspirants out of office could roughly equal the number serving in one.
Republican office-holders mentioned as possible candidates include three senators - George Allen of Virginia (who is up for re-election this fall), Sam Brownback of Kansas and John McCain of Arizona. Also, Rep. Tom Tancredo of Colorado is considering a protest candidacy based on his intense opposition to illegal immigration.
Five Democratic senators are possible contenders - Hillary Rodham Clinton of New York, Evan Bayh of Indiana, Joseph R. Biden Jr. of Delaware, Russell D. Feingold of Wisconsin and 2004 nominee John Kerry of Massachusetts - as well as New Mexico Gov. Bill Richardson (who, like Clinton, is favored for re-election this year).
Results over the past 50 years give the edge in presidential contests to candidates with a political day job.
Leaving aside incumbent presidents, the two parties since 1956 have picked 12 nominees who held an elected position when they were chosen. Over that same period, five nominees did not.
Of those five, two were former vice presidents (Republican Richard Nixon in 1968 and Democrat Walter Mondale in 1984). Another was a repeat nominee, Democrat Adlai Stevenson, nominated to run in 1956 after losing to Dwight D. Eisenhower in 1952.
Republican Ronald Reagan, the former governor of California, won the GOP nomination in 1980 after building a national following by nearly toppling President Gerald R. Ford in a 1976 primary challenge.
Thus, the only candidate in 50 years who lacked previous national exposure, was out of office and won a presidential nomination was former Georgia Gov. Jimmy Carter, the Democratic Party's choice in 1976.
Despite this history, several top strategists from previous presidential campaigns said they believed that candidates without a political office enjoy distinct advantages.
"It is far better to have a candidate who is loose and not affiliated," said Donna L. Brazile, who managed Gore's 2000 campaign.
John Sasso, who served as a senior adviser to Kerry and 1988 Democratic nominee Michael S. Dukakis, added: "Every once in a while, there is an advantage of being in office because you can deal with a real world event. But by and large, it's a lot of downside, because it takes away focus from something that needs 100 percent-plus attention and concentration."
Brazile and other strategists say that the biggest plus for the out-of-office candidates is a more flexible schedule. Especially valuable is the chance to lavish time on voters in the early caucus and primary states.
William Shaheen, a prominent New Hampshire Democrat, said former Sen. Bill Bradley of New Jersey, in 2000, and former Vermont Gov. Howard Dean, in 2004, surged to early leads in the state's Democratic primary battles "because they were here all the time."
Both, however, lost the contests: Bradley to Gore and Dean to Kerry.
The main trade-off between those in office and those out of office when they run for president might involve the sort of exposure they receive.
The officeholders can more easily attract national coverage, but the candidates without an elective post can accumulate more face time in Iowa and New Hampshire living rooms.
Less than two years from now, voters in those two states will provide new evidence to fuel the old arguments about which kind of visibility is more valuable.
Ronald Brownstein writes for the Los Angeles Times.