Someday, somewhere over the rainbow, New Jersey voters will have a choice between two impressive candidates for governor. But not this year.

Our choice is Democrat Phil Murphy, by default. He has profound weaknesses, starting with his lack of political experience, and his ferocious loyalty to the public worker unions, the same two weaknesses that sank former Gov. Jon Corzine.

But Lt. Gov. Kim Guadagno, the Republican candidate, is the worst nominee of either major party to come along in decades. Her knowledge of the issues is paper-thin, she's failed utterly to separate herself from the disastrous legacy of Gov. Chris Christie, and she has surrendered her integrity with dishonest attacks on her opponent designed to inflame bigotry against immigrants.

If you are conservative, know that Guadagno, not Murphy, is proposing the single biggest spending program of this campaign -- a convoluted plan to relieve property taxes costing $1.5 billion a year. She offers no means to pay for it, only a promise to find waste, somewhere.

Consider that: Guadagno presents herself as a small-government conservative, but she can't identify any significant state spending programs she would cut.

That speaks volumes. Guadagno hasn't done her homework. Press her on tough issues such as school funding or Port Authority reform, and you hit nothing but brick walls. She seems to think she deserves this job because she is next in line.

Worse, Guadagno has turned dark in recent weeks. First, she slandered Murphy with a dishonest TV ad charging he would protect criminals who are in the country illegally. Now she proposes to cut state aid to any local government that refuses to use its police force as an arm of President Donald Trump's deportation army.

Murphy, for the record, never suggested that New Jersey should protect criminals. Guadagno's team spliced a video to make it seem that way. He would not block federal agents from deporting unauthorized immigrants either.

He only wants to follow the advice of police leaders in cities like Newark and Jersey City who say that using local police to enforce immigration laws would drive immigrant witnesses and victims underground, making it harder for police to catch bad guys. It would make us all less safe, they warn.

Would Guadagno really overrule the professional judgment of these police and cut the state aid these cities need? This is a sign of desperation, unrestrained by principle or simple decency. It would lead inevitably to mass police layoffs.

Guadagno's attitude toward Trump is also a confused mess. After the groping tapes emerged during last year's campaign, she refused to endorse him, to her credit. But in the final days of the campaign, she recorded a robocall urging voters to support him, a reversal she's never explained. What sense does that make?

The real weight pulling down Guadagno, though, is Christie. Her loyalty to him was absolute for eight years, beyond what we see even in many vice presidents to their presidents.

Listen to her own words. When asked about Christie leaving the state so often to run for president, she dismissed any concern, saying she was his political clone anyway. "We were completely together on every issue," she said.

As governor, she says, she'd stick with his vetoes of gun laws, and his cuts to family planning programs. She believes his claims of ignorance on Bridgegate, even though five sworn courtroom witnesses exposed him as a liar. She says she voiced objections on policy and politics in private meetings with Christie, but she won't point to a single example. Please. She opposed the gas tax hike, but offered no substitute.

None of this stands up to scrutiny, any more than her platform does. Even conservative voters should resist pulling the lever for Guadagno and lowering the bar that much. In the primaries, Republicans had a strong candidate in Assemblyman Jack Ciattarelli, R-Somerset, and they blew it.

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So, why Murphy, aside from the fact that he is not Guadagno?

For one, he would reverse many of Christie's errors. He would rejoin the regional pact to fight climate change, cutting emissions at power plants and raising money for other green initiatives. He would restore money to Planned Parenthood, and sign sensible gun control laws. He offers a promising plan to establish a state bank, and use government deposits to provide cheaper loans to small businesses and college students, cutting out the middlemen on Wall Street.

He is socially progressive, like New Jersey. He chose as his running mate Sheila Oliver, the former Assembly speaker, an African-American, who can help him navigate Trenton. He would raise the minimum wage; he is a full-throated supporter of gender equality; his service on the board of the NAACP signals a commitment to racial justice; he promises to fight the fanatics at the NRA; and he's won the universal endorsement of environmentalists.

What about taxes, though? Guadagno warns that Murphy's liberal agenda will force him to raise taxes on everyone. So, let's take a look.

Murphy proposes a tax hike of $1.3 billion a year, about one-quarter the size of former Gov. Jim Florio's, adjusted for inflation. Just over half of it would come from a modest surcharge on annual incomes over $1 million. Of the remainder, about half would come from closing an outrageous loophole that allows companies to avoid paying their fair share by shifting paper profits to other states, a loophole that most states have already closed. The rest would come from a tax on the sale of legal marijuana.

So, if that's the end of it, middle-class families have nothing to fear. But would Murphy layer on other tax increases to fund his long list of liberal ambitions?

He says his three top priorities are to fully fund the K-12 education formula, stick with the ambitious schedule of increased pension payments, and make a $100 million down payment on transit fixes.

The good news is those are indeed the most urgent priorities. And Murphy's boost in school aid would do more to reduce property taxes than Guadagno's fake promise of relief.

The bad news is his $1.3 billion tax hike won't solve the problem. It will not even cover the full cost of these top priorities, let alone Murphy's long list of liberal ambitions, including free tuition at community colleges, fresh efforts to build affordable housing, new subsidies for day care, and bigger tax breaks for the working poor.

Will Murphy restrain himself and stick to his three top priorities, given the fiscal crisis? If so, he's misleading voters by painting this unrealistic and utopian vision. And if not, then fears of broader tax increases are well-founded.

Murphy's allegiance to the public worker unions is even more unnerving, especially his romance with the New Jersey Education Association, the single richest and most powerful special interest group in the state.

The NJEA, unlike the other unions, is militantly opposing any cuts to their health benefits. It is constantly trying to block the expansion of charter schools in Camden and Newark, which outside groups rate as among the best in the country. And this year, it is spending huge sums to back a Trump supporter in South Jersey who is trying to unseat Senate President Steve Sweeney, the top Democrat in the Legislature.

Murphy, like a hostage with a knife at his neck, won't make a peep about any of this. That raises doubts about his judgments, and concern that he may have made promises to the union behind closed doors in return for its support.

But if Murphy stands in the way of the charters, he'll have to explain to poor families in our cities why the NJEA is more important to him than they are. If he stands with the union on health benefits, he'll have to raise taxes more to cover the outrageous cost. And by standing with the union in its fight against Sweeney, he is sowing doubts in the Legislature about his political competence, and his loyalty to the party he now leads.

This race is depressing. What we need is a centrist Democrat, a progressive who is also a fiscal realist with an arm's-length relationship to the public worker unions. That person is not on the ballot.

But, please, don't throw away your vote on a third-party candidate. Politics is not about feeling good and pure; it's about having an impact. Our next governor is going to be Murphy or Guadagno, and the difference is important.

Face that fact, and make it Murphy.

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