Boston ? Sometimes it isn’t just the answer to a poll question that tells you everything you need to know about public sentiment. Sometimes the question itself is sufficient.

Here’s the question, asked in The Boston Globe’s latest survey of public opinion, that sums up the prevailing (really bad) mood:

Do you trust current political incumbents to provide leadership in Washington and Massachusetts or do you think political incumbents in Washington and Massachusetts need to be replaced by a new crop of leaders?

Remember that this question was asked in a state where the governor is a Democrat, where for 31 of the last 32 years both the senators have been Democrats, where for the last 14 years all 10 members of the U.S. House have been Democrats, where the Democrats hold 90 percent of the seats in the state House and 88 percent of the seats in the state Senate, and where the Democrats have prevailed in every presidential election but two in the last half century.

I can guess what you’re thinking: To ask this question in a political year like this one is to answer it.

You’re right, but the answer itself is startling. More than half of those in the Massachusetts survey say they want a new crop of leaders. These are people who provided the Democratic presidential nominee, Sen. George S. McGovern, with his only state in 1972 and who have kept the Democrats in power in the state legislature for the past 55 years.

Here is the understatement of the day: This looks to be a Republican year.

It’s an anti-incumbent year, too, but when one party is in power in the White House, both houses on Capitol Hill, twice as many state legislatures as their rivals and just over half the governor’s chairs, being anti-incumbent and being anti-Democrat in many cases amounts to the same thing.

There’s no other explanation for the trouble that Democratic Sen. Michael Bennet is experiencing in Colorado, where he trails Republican Kent Buck in a state Barack Obama took by 214,987 votes only two years ago — and where the governor, both senators, five of the seven U.S. House members, and both houses of the state legislature are Democratic.

Nor is there another plausible explanation for the difficulties three-term Sen. Russ Feingold is facing in Wisconsin, where he trails Republican Ron Johnson in a state that Obama captured by 414,818 votes in 2008 — and a state where the governor, both senators, five of the eight U.S. House members and both houses of the legislature are Democratic.

There are exceptions, of course. Gov. Charlie Crist, once virtually anointed the next senator from Florida, isn’t exactly an incumbent, but he’s no longer the favorite to win the seat and isn’t even running as a Republican anymore. That’s a direct result of the early stirrings of the tea party.

Part of the problem comes from the Democratic top, which is ironic because much of the energy that propelled the Democrats into their commanding position came from the top in the first place. It was Barack Obama who set the Democrats free to dream of a new age, who brought many of them to power and whose difficulties in Washington are one of the principal reasons their dream and power are in jeopardy.

To onetime friend and longtime foe alike, Obama this autumn appears much the way David Lloyd George, the Liberal Prime Minister of Great Britain from 1916 to 1922 appeared to John Maynard Keynes, the British economist — “an instrument and a player at the same time, which plays on the company and is played on by them too; he is a prism … which collects light and distorts it and is most brilliant if the light comes from many quarters at once.”

But the light has dimmed and the quarters have shrunk. Obama’s party is fighting for its political life and, if he didn’t still have 25 months before the next presidential election to change the public’s perception and the examples of Franklin Roosevelt (1938), Ronald Reagan (1982) and Bill Clinton (1994) to comfort him, it would be fair to say that Obama were fighting for his political life as well. As it is, he is fighting to shape his political future.

Obama has done that before, of course, for it was he who produced the sunny horizons the Democrats envisioned at his inauguration in January 2009.

The task Obama has before him is to change the narrative that his rivals — not just the Republicans but their comrades in tea — have created in an almost flawless effort to control the political conversation.

In that conversation, Obama — considered barely an American, let alone a Christian, and perhaps a socialist — no longer stands as a symbol of American possibility but as a symbol of shrinking American prospects, willing to junk capitalism, embrace our enemies and jeopardize America’s independence and future. This is not a period of temperate discourse, to say nothing of civility.

Obama created the Democrats’ opportunity and then he contributed to the Democrats’ peril. Now — perhaps too late for November, but not too late for November two years hence, when he runs for re-election — the president faces the challenge of changing the conversation and the political environment again.

The Republicans will have their own problems after November, as the tensions born of victory by the GOP and the tea party will suddenly become the burdens of victory. The prize-turned-curse of a big, energized, idealistic coalition that Obama inherited will be bequeathed to his rivals on the right. The charge of what to do with victory will become the Republicans’, and the opportunity to play the foil will again redound to the Democrats.

This summer a French magazine carried this cover story: “The 2012 Presidency: Has He Already Lost?” The story was about Nicolas Sarkozy, but the talk on this side of the Atlantic is about Barack Obama. Two years from now we’ll see if incumbency remains a disadvantage — and who pays if it is.