Limiting taxes: It's constitutional
Republicans in the House have passed CACR 6, to require a 3/5ths majority vote of the Legislature to raise taxes or fees or impose new ones, and CACR 13, to ban a personal income tax in New Hampshire. (The Senate has amended CACR 6 to require a 3/5ths majority to raise spending above the rate of inflation, rather than to raise taxes.)
This being New Hampshire, most Democrats don't want to state openly their preference for having no limits on the state's power to tax or spend. So they have staked their opposition to these amendments on the phrase, 'tax policy doesn't belong in the constitution.' This is a principle that no one familiar with constitutional history can possibly believe.
Saying that 'tax policy doesn't belong in the constitution' is like saying that beef doesn't belong in hamburgers. One of the primary reasons the English-speaking people developed constitutions was to limit the state's taxing authority. Such limitations are in both the U.S. Constitution and the New Hampshire Constitution, and their history stretches back to the Magna Carta, which limited how the king could tax the nobles.
Either New Hampshire's Democrats haven't the slightest clue about the constitutions under which this state and nation operate, or they are, again, making a deliberately misleading argument to hide their own real motives...