This is a dangerous time for Hillary Clinton.

It's nothing the Secret Service needs to worry about, as New York's junior senator zips through Iowa, where I followed her last weekend, and other early caucus and primary states.

It's that the usual bull's-eye on Clinton's back has grown much bigger, the result of the closer scrutiny reserved for all front-runners, more intense attacks from opponents and her own recent mistakes in debates and on the trail.

Parlaying a rich abundance of cash and her enduring cachet, she has convinced a lot of once-skeptical voters that she is a complete leader — smart and strong, warm and funny — who can advocate for the poor, manage the economy and command the military.

But Clinton's overall performance and polling, and her opponents' failure to gain much traction, may have raised expectations and standards beyond those for other candidates — even higher than her campaign had planned. The perils of this are especially apparent in Iowa, where months ago Clinton was not expected to win on Jan. 3 but now leads in one of the closest Democratic primary contests.

In Des Moines, hours before the boisterous political beauty pageant that precedes the nation's first nominating vote, every utility pole, every sidewalk crack big enough to jam a spike into, every patch of soil around the trees lining Fifth Avenue sported red, white and blue placards for Hillary Clinton.

The work by thousands of volunteers outside and inside the auditorium was a stunning display of the organizational strength that, beyond money and charisma, really wins in Iowa. But by the time the 9,000 Democrats arrived for the Jefferson-Jackson Day dinner on Nov. 10, there were strong signs of — and for — her competitors.

Supporters of Barack Obama were especially "fired up" and "ready to go," as they would chant all night. The campaign shrewdly used a concert by John Legend as a magnet for thousands who, clad in red T-shirts, then marched noisily to the hall.

John Edwards was at his best, even though his supporters numbered fewer than Obama's or Clinton's. His passionate populist appeal eclipsed Clinton's lower-keyed, broad-themed argument for her candidacy. Then Obama, speaking last by lot, leaped over both of them with a powerful speech that, while not mentioning her by name, skewered Clinton relentlessly.

Most of Iowa's political and pundit class opined that Obama thus established himself as the guy to beat here. "Clinton opened the door by merely being good," said state Rep. Dolores Mertz, 82, the grande dame of Iowa's Legislature, who is not supporting any candidate. "Obama walked right through it."

Only months ago Clinton could have said that coming in second on Jan. 3 would be a "victory" in this state with its quirky voters (Democrats are more liberal and Republicans more conservative than in many others) and quirkier caucus (a candidate can have more supporters show up at the 1,800 precincts but still lose handily). No longer; expectations have changed perceptions.

Not that a loss here would cripple Clinton, whose base of committed supporters, many of them women, may be more reliable to vote on Election Day. But beyond Iowa she will face the same challenges.

She can't afford to have a junior aide planting an innocuous question in the crowd, as happened earlier this month on an Iowa campus. She can't afford to give slick or contradictory answers, as she did to a debate question about allowing undocumented workers get driver's licenses in New York. She can't afford to turn off male voters, much less the media, by insinuating that the "boys" are ganging up on her — even if maybe they are.

Being "good" won't be good enough for someone who still faces so much skepticism. "If you can't stand the heat, get out of the kitchen," Clinton told the Jefferson-Jackson crowd. "Well, I feel really comfortable in the kitchen."

She'd better be. The kitchen — the crucible of a competitive presidential campaign — will be hotter for her than for any opponent.

Lawrence C. Levy is a columnist for Newsday. Reach him at lawrence.levy@newsday.com.