When the going gets tough, the tough go negative. Scott Brown played nice until Elizabeth Warren pulled ahead in four out five recent polls.

Both candidates received heaps of praise for making a pact to keep PACs and other outside groups from running ads in Massachusetts, a gesture that helped bring some civility to what promised to be a bruising campaign for the US Senate.

Promises, promises. Brown appears determined to continue to hit Warren hard and often for her assertions about her American Indian heritage. The campaign’s latest ad unleashes a barrage of news clips hitting Warren for her heritage claims and for misusing minority status to advance her career.

Brown may have tipped the scales this time… against himself. Taken at face value, the ad probably would have been chalked up as more of the same from Brown on the Warren heritage/affirmative action question.

But the Brown campaign made a major tactical error when a group of the senator’s supporters and staffers descended on a campaign rally with tomahawk chops and war whoops. Somehow, somewhere, someone forgot that those gestures have a long history of controversy, um, because American Indians find them highly offensive.

Brown compounded his problems by issuing less than a full- throated apology. The Boston Globe’s Brian McGrory delivers a reality check to the image of Brown as affable everyman.

The senator gets into trouble over at Talking Points Memo for his “she don’t look Indian?” comment about Warren during the first debate. TPM points to a little-known fact that the late US Ambassador to Libya, Chris Stevens was a member of the Chinook tribe. Josh Marshall asks, “So, does Chris Stevens meet Brown’s ‘know one when I see one’ test?’ ”

American Indian groups have come down hard on Warren. But they have come down harder on others who disrespect history. Earlier this year, the Native American Journalists Association expressed skepticism about Elizabeth Warren’s ancestry but found some media outlets’ use of “witty” headlines to mock Warren even more appalling. “While allegations surrounding her claims are unsettling, making fun of Native names that have history, respect, and honor is worse,” the association said

The senator is discovering, as former lieutenant governor Kerry Healey did in the 2006 gubernatorial race, that failure to appreciate the nuances of race, culture, and history can be a candidate’s undoing. Healey’s ad attacking Deval Patrick, then an unknown corporate executive and former Justice Department official, backfired.

The campaign ad featured a white woman walking toward her car in a dark parking garage. “Have you ever heard a woman compliment a rapist?” the voiceover intoned, adding that Patrick called a man who he thought had been wrongfully convicted of rape, “thoughtful” and “eloquent.”

Designed to play to white women’s fears about black men, equating Deval Patrick with a convicted rapist did Healey no favors. Already slipping in the polls, Healey plummeted further and lost the election in a landslide.

Warren’s riposte to the Brown ad is succinct: “Scott Brown can continue attacking my family, but I am going to keep fighting for yours.”

The strategy of labeling Warren as a Native American wannabe who wrongly benefited from affirmative action has run its course. The Brown campaign would be wise to move on.

                                                                                                                            –GABRIELLE GURLEY

BEACON HILL

The former chemist at the center of the burgeoning state drug testing scandal did not have a master’s degree from UMass, as she claimed.

Though arguments about the need for jobs amidst the recession became the biggest fuel behind the state’s approval of casinos, the first gambling halls might not open until 2016, according to the state gambling commission.

Gov. Deval Patrick announces $4 million for community colleges.

MUNICIPAL MATTERS

Brockton Mayor Linda Balzotti will return to the process of asking city councilors for their input for road repairs after one councilor voted against her spending request because members weren’t consulted.

Property owners along Scituate’s Humarock Beach posted no trespassing signs and are considering putting up a fence after the town discovered it only had legal right of ownership to 300 feet of the popular beach.

Dartmouth officials closed down a Route 6 motel for failing to correct a number of health violations, some dating back to 1988.

Large-scale solar projects proposed in Lunenburg took a major step toward approval Tuesday after residents voted to approve components of the projects.

NATIONAL POLITICS/WASHINGTON

In an editorial, the Herald argues that the State Department and Obama administration overreacted to CNN’s use of Ambassador Stevens’ journal in its reporting.

The Phoenix’s Peter Kadzis wonders if Bill Clinton’s highly acclaimed speech to the DNC will prove to be Hillary’s 2016 campaign kickoff.

ELECTION 2012

The Globe raises some unwelcome tax questions for US Rep. John Tierney, whose reelection is threatened by a messy case of illegal, offshore gambling involving his wife and her ne’er-do-well brothers. As of Tuesday afternoon, the Salem Democrat had not released any tax returns, as he has vowed to do. Nor could he show the Globe evidence that he has done so in the past, despite claiming earlier this year that he has released them “in every election.” Republican Richard Tisei, meanwhile, did not pay federal income taxes for two years due to business losses.

The Herald asks what would the late Sen. Edward M. Kennedy think of Warren’s work for LTV Steel, a company Kennedy railed against.

In a Globe op-ed, Jon Keller offers a behind-the-scenes look at last week’s Brown-Warren debate, concluding that it offered a revealing look at the candidates but little in the way of substance. Globe columnist Scot Lehigh examines Brown’s “Senate-control problem.”

Scott Brown decides to pick a fight with Secretary of State William Galvin over absentee ballots.

A Quinnipiac University/New York Times/CBS poll shows President Obama with a widening lead over Mitt Romney in Ohio and Florida, two critical swing states in this election.

No going back now: The deadline for Todd Akin to drop out of the race for US Senate in Missouri passed yesterday.

BUSINESS/ECONOMY

US News & World Report asks: Is the American dream dead? CommonWealth wondered about that in last fall’s special issue.

Some local industries are having trouble finding skilled workers, even as the unemployment rate remains high, the Attleboro Sun Chronicle reports.

EDUCATION

The school committee in Tiverton, Rhode Island, just over the Massachusetts border, unanimously approved the use of Breathalyzers on any high school student suspected of drinking.

Mary Fifield, president of Bunker Hill Community College, is set to retire, the Boston Business Journal reports.

HEALTH CARE

The UMass Memorial Health Care System plans to eliminate 140 full-time jobs, NECN reports.

TRANSPORTATION

Jetsons alert: California passes a law setting up regulations covering self-driving cars.

CRIMINAL JUSTICE

A Lawrence police officer is indicted for allegedly steering towing business to a company that returned the favor by providing him with a “stream of benefits,” including a $4,000 snow plow, the Eagle-Tribune reports.

The Suffolk DA’s office and BPD failed to record details given to them by the survivor of a Mattapan multiple shooting, including the identity of the shooter, the Herald reports.

MEDIA

Keller@Large sides with the New York Times over its decision to keep using the term “illegal immigrants” because they actually are both.

The Nieman Journalism Lab examines the Philly Rap Sheet, which tracks arrests in Philadelphia.