Hillary Rodham Clinton answers questions at a news conference at the United Nations in New York on March 10, 2015. Clinton conceded that she should have used a government e-mail account to conduct business as secretary of state. (Richard Drew/AP)

For many months, Democrats have claimed they want an open competition for their party’s 2016 presidential nomination, although many didn’t really believe it. They were actually content to see Hillary Rodham Clinton run virtually unopposed. This week, some of them must be rethinking.

As Bill Clinton always says, campaigns are about the future and not the past. If that doesn’t worry Democrats right now, it should. One of Hillary Clinton’s biggest challenges, assuming she runs, will be to make herself a candidate of the future. This week, she’s trapped in a rerun of the past.

The absence of a strong Democratic bench has never been more apparent. Clinton is embroiled in a controversy over her e-mail practices as secretary of state that has seemed to friend and foe like a repeat of the old days. Yet real competition for the nomination remains minimal to nonexistent.

[Clintons and controversy: The circus is back in town]

Clinton has been such a dominant front-runner that she has smothered most potential competition. Who rightly thinks they can seriously compete with her for money or institutional support? The Clinton operation that is being built in preparation for the campaign — coupled with the outside forces that already are up and running to protect her from attacks — should make any sensible potential Democratic challenger think twice about going up against it.

And yet, a presidential nomination is too important to be handed to someone on a platter, especially at a time like this. The end of a two-term presidency is a time when a political party needs to refresh itself. Whether the incumbent president is popular or unpopular isn’t the issue. It’s whether a party is looking for genuine debate and disagreement about its future direction — and finds a way to showcase its future leaders.

No one should underestimate the attributes that Clinton brings to her prospective campaign. Compared with most others (one exception being Vice President Biden), she starts with skills, knowledge and experience that few in her party can match.

She has familiarity with the highest levels of government, perspectives from the White House, the Senate and the State Department that inform her ideas and judgments. She is, in the vernacular of the Senate, a workhorse, not a show horse. She knows policy far better than most.

She has weathered political fights for years, emerging both tougher and warier. She is neither new nor inspirational in the way President Obama was in 2008, although the possibility of electing the first female president gives a historic lift to her candidacy.

Her main calling card — beyond gender — could well be the opposite of hope and change. It could be that, at a time of some intractable problems, she knows how to get things done, that she doesn’t give up, that she is prepared to inch forward day by day, month by month, whether dealing with long-standing issues or unexpected crises. Many people could find that profile reassuring in its workaday style.

If Biden were a young man, he would probably be a candidate, and Democrats might have a genuine debate. But although vigorous and still youthful in appearance, he is of an age and wise enough to know what the odds are of taking on Clinton even as a sitting vice president.

Even if Biden were to challenge Clinton, it would be a fight within the Obama family — two of the highest ranking members of his administration with decades of service trying to sort out the future. But they would be encumbered by what the president has done or not done and by how history in the short term has judged him. They would represent a debate about continuity, not continuity vs. some kind of change. That alone wouldn’t be ideal for the party either.

Former secretary of state Hillary Clinton told reporters at the U.N. that she chose to use a personal e-mail account because she thought it would be easier to use one device rather than two. (UN Web TV)

In a more perfect world, there would be challengers for the nomination from a different generation, the generation, say, of Martin O’Malley, the former governor of Maryland, or from a different wing of the party than either Clinton or Biden represents, the wing now described as owned by Sen. Elizabeth Warren (D-Mass.) But the power and reach of the Clinton network has so overshadowed everyone else that prospective rivals have virtually disappeared.

[Martin O’Malley really doesn’t want to discuss Hillary Clinton’s e-mail]

Without formally announcing her candidacy, Clinton has been on a path that would give her the nomination almost by acclamation. Now Democrats can see with greater clarity a more complete balance sheet on the person on whom they are betting their futures: Many assets for sure, but liabilities that are overlooked or dismissed until they shout for attention.

The e-mail controversy is not going away soon, given questions left unanswered by Tuesday’s news conference and the determination of Republicans and the House Select Committee on Benghazi to keep asking for more information.

That’s not to say the e-mail matter alone will cause Clinton political problems a year from now or in November 2016. This being the age of Twitter, controversies come and go quickly, attention spans are short and partisan polarization often has as much or more to do with how people interpret something as it has to do with the facts.

Voters will decide what is important and what isn’t, apart from any efforts by Clinton’s opponents or the media. She is no doubt counting on this controversy fading into the background long before political judgment days arrive, hoping that enough people will judge it at worst a minor infraction or a media-generated distraction, rather than something disqualifying.

What presents the greater risk is that the lasting effect is not the question of whether she violated federal regulations or guidelines, but rather that voters simply grow tired of all the drama and wonder whether a Clinton presidency would mean another four or eight years of it.

For Democrats, institutionally and collectively, the stakes are high. Victory in the 2016 general election is far from certain, whatever the demographic trends. Those who claimed they wanted a competitive nomination contest, even if they didn’t really want it or assumed it would not happen, must think now that it would be more valuable than ever.

That still looks unlikely, but without it, Clinton will be running mostly against herself for the next year and some months, and as the past week has shown, that’s not always in her best interest.