For a few years now, politicians straining against all of the antigovernment demagogy have been searching for a way to energize public interest and remind voters of the essential government services and protections they rely on and all too often take for granted.

President Obama has struggled to find that language, only recently beginning to draw a clear contrast between his goal to revive the economy and put Americans back to work and the stagnation that is the inevitable result of the Republicans’ antitax, antispending policies.

While most other Democrats are afraid to talk about the need for higher taxes and are running away from the problem, Elizabeth Warren, the leading Democratic candidate for a Senate seat in Massachusetts, has engaged the fight and is beginning to rally supporters.

Ms. Warren talks about the nation’s growing income inequality in a way that channels the force of the Occupy Wall Street movement but makes it palatable and understandable to a far wider swath of voters. She is provocative and assertive in her critique of corporate power and the well-paid lobbyists who protect it in Washington, and eloquent in her defense of an eroding middle class.