Sen. Bernie Sanders (I-Vt.) may be poised to win both the Iowa caucus and the New Hampshire primary, and as Sanders soars, rival Hillary Clinton is making the worst possible move of launching an all-out attack against him, which is the same mistake she made when she attacked Barack Obama in 2008.

For some time, I have strongly advised people close to the Clintons to not go negative against Sanders. Clinton needs to inspire voters about why she should be president, not become a negative candidate who reminds voters of the kind of politics they want to end.

Remember -- and this is a key point -- that when Clinton attacks Sanders for the vision and programs he believes in, she is attacking the large numbers of Democrats and independents who believe in what Sanders believes and favor the same changes and reforms that he promotes.

The Clinton attack against Sanders is the worst possible move for her and for Democrats. Because Clinton has low ratings for trustworthiness, whereas Sanders's ratings are high, a Clinton attack against Sanders will backfire.

Even worse for Clinton, the problem is that she has never articulated an uplifting and exciting reason for voters to back her, and her negative attack against Sanders will drown out any positive message she may have, if she has one.

Clinton's attacks against Sanders sounds strangely similar to her attacks against Obama in 2008. She is charging -- among many things -- that Sanders does not offer a realistic program, which is both condescending and wrong and an insult not only to Sanders, but to the large number of Democrats who are with Sanders.

What a presidential candidate should do is offer a panoramic vision of how America can become better, mobilize support for that vision, seek an election victory with a mandate, and then negotiate with Congress from strength and make the compromises that must ultimately be made to win the most dramatic possible reforms. That is what important presidents such as Franklin Roosevelt and John Kennedy did. That is what Sanders is doing.

What a presidential candidate should not do is identify with the status quo and oppose dramatic change even before the first ballot is counted and attack the change candidates as naive or unrealistic. This is what Clinton is doing with her negative attacks against Sanders.

Sanders proposes a healthcare system based on Medicare for all. Is Clinton criticizing all the Democrats and independents who agree with him? Would she have attacked Presidents Kennedy and Lyndon Johnson for proposing and enacting Medicare in the 1960s?

Sanders proposes a free public college education, paid for by a transaction tax on Wall Street speculators. Is Clinton criticizing young people and their moms and dads who would benefit greatly from a free public college education, or is she criticizing voters who favor a modest and fair speculation financial tax that would ask wealthy individuals and Wall Street firms to do more, to pay their fair share to help the next generation of students learn?

Sanders proposes bringing back the Glass-Steagall Act and breaking up big banks. Is Clinton attacking as naive and unrealistic the huge number of voters who favor breaking up big banks? Would Clinton have criticized Franklin Roosevelt as being naive and unrealistic when he pushed the original Glass-Steagall Act to passage in the 1930s?

Sanders proposes an increase in Social Security benefits at a time when those benefits lag far behind the cost of living for seniors. Is the Clinton attacking the senior citizens who deserve better than the status quo, in which this year seniors receive no increase in Social Security benefits at all?

Sanders is tapping a deeply held yearning in the electorate for big change and a nobler politics, and when Clinton attacks him for it, she is attacking the voters who demand this change and aligning herself with the lobbyists and special interests who oppose the very change and reforms that most voters want.

So as Sanders soars, Clinton attacks him, which gives Sanders the upper hand as Iowa and New Hampshire prepare to vote.