Since presenting his tax and budget plan last month, Gov. Paul LePage has been on the road selling it to audiences around the state. The response from Democrats, cast as the opposition party since the November election has been — silence.

Individual Democrats have, in fact, criticized parts of the plan — ending municipal revenue sharing, for instance, or transferring still more of the financial responsibility for schools to the property tax. But about the big elements of the plan — dramatically raising the sales tax while lowering the income tax — they have nothing to say.

This must change. The foundations of Maine’s tax system are where they are for good reason, and those seeking to alter them should have to prove their case — and there must be an informed critique from those with different political beliefs.

Begin with the basics: There are two big questions about any tax system. First, does it raise enough revenue to do the things — educate Mainers, maintain the roads, administer justice — that state government is supposed to do, and do well? Second, does it raise that money so the burdens are fairly distributed, and tax collection is as efficient as possible?

So, are state revenues sufficient? During LePage’s tenure as governor, aid to K-12 education has stagnated, and actually is projected to decline over the next two years. Since the onset of the Great Recession, state aid per pupil has shrunk, in constant dollars, by 13 percent.

The Maine Municipal Association’s cost surveys taken in 2008 and 2012, before and after LePage’s first budget, show that while municipal spending on administration fell by 10 percent, local school spending increased by 19 percent, or $200 million. That was largely as a result of the state failing to meet the statutory requirement of 55 percent funding.

And if revenue sharing is zeroed out as LePage proposes, a $158 million item, that will mean more than $350 million per year will have been added directly to property taxes, unless towns and cities undertake further rounds of cuts.

Higher education fares no better. After six years of flat funding, meaning reductions in constant dollars, the University of Maine System gets a small increase in the latest LePage budget, but the community colleges must again do with less.

Education funding regularly ranks as Mainers’ highest priority. In a state with the lowest incomes in New England, and few alternate paths to creating better jobs, this suggests that the budget plan is inadequate. The $300 million-$400 million tax cut LePage now proposes, on top of the $500 million in reductions made in 2011, will only make matters worse.

The other test is fairness and efficiency. In this respect, income taxes are the most efficient tax we have. The state income tax piggybacks the federal tax return and, fortunately, the state form is a lot simpler and easy to file. Expanding the sales tax, as LePage suggests, will mean thousands of new small businesses will file sales tax reports, something that should at least be considered before treading this path.

Fairness is an elusive commodity. But consider the trajectory of the national and state economy over the past three decades. The proportion of income going to the top 10 percent of taxpayers has mushroomed, while everyone else’s incomes have stagnated. LePage proposes that the richest Maine taxpayers pay 5.75 percent to the state, down from 8.5 percent before 2013, while those just doing well — adjusted incomes of $50,000-$190,000 — pay more, a 6.5 percent rate.

The numbers are still being crunched, but it appears that the top 10 percent of Maine taxpayers will save, on average, $7,000 per year, on top of $3,000 saved in the 2011 tax cut. As for everyone else, the savings are exceedingly modest, and likely outweighed by increased property taxes the plan also will produce.

On the other end of the economic spectrum, consider the cigarette tax, the only major state tax increased permanently in two decades. It now stands at $2 per pack. As a proportion of retail price, this amounts to a sales tax of 35 percent, against the general sales rate of 5.5 percent.

We know who pays this tax — the lowest income people in Maine. While justified as a health measure, it also means that those with the least ability to pay face the highest tax rates. And those with the greatest ability to pay get another big tax cut.

So for fairness, as well as revenue adequacy, the LePage plan has major failings, something you’d never know from the debate so far at the State House.

Are there alternatives we might consider? We’ll take a look at some next time.

Douglas Rooks has covered the State House for 30 years. He can be reached at drooks@tds.net.