AT FIRST GLANCE, State Senators Brian Joyce and Cheryl Jacques appear to have nothing in common. Joyce lives in Milton with his stay-at-home wife, Mary, and their five children. Jacques lives in Needham with her partner, Jennifer Chrisler — a former Internet executive now working as the finance director of the Jacques congressional campaign — in a double-income, no-kids household.

Dig a little deeper, however, and the two couldn’t seem more alike. Both went to suburban public high schools, graduating in 1980. Both graduated from Boston College in 1984. Both attended Suffolk University Law School. Both are Catholic.

And that’s not all they have in common. Both have changed positions on sensitive social issues at the beginning of political campaigns. Joyce kept his switch in favor of abortion rights private until the race for the Ninth began; Jacques, who was running for lieutenant governor before jumping into the congressional contest, did the same with her position on the death penalty (from pro to anti) until the state Democratic convention in June. Both are also making a play for gay voters. While Jacques has the obvious advantage, Joyce has tried to emerge as a champion of gay rights. He chaired a hearing on domestic-partnership legislation last month, a move that won praise from Jacques in the week before she publicly mulled getting into the race.

Even more significant is the make-up of their projected electoral bases. Both Jacques and Joyce are classic suburban candidates who want the district’s progressive voters to send them to Washington. Jacques is winning endorsements from big national groups: Planned Parenthood, EMILY’s List (a national political-action committee that supports pro-choice, female candidates), and the Human Rights Campaign, the country’s largest gay-rights group. And though Jacques has the edge on endorsements, Joyce is doggedly sticking to the campaign trail in pursuit of liberal voters on the ground. In short, Jacques and Joyce are driven, relentless campaigners who share the same goal.

Both candidates’ aggressive campaign styles were on display during last week’s second debate among contenders for the Ninth, hosted by WLVI (Channel 56) political reporter Jon Keller. Before the debate began, Jacques asked Keller which camera she should look at during the intro. Keller told her to look right at him — standard instructions for those unfamiliar with live television appearances. A few moments later, Keller introduced Jacques, Joyce, and the other participants, State Senators Marc Pacheco of Taunton and Stephen Lynch of South Boston. Pacheco and Lynch looked directly at Keller, but Jacques and Joyce ignored the moderator and turned their heads to face the camera like seasoned TV personalities — smiling.

During the debate, when asked whether they supported a constitutional amendment against flag burning, both Jacques and Joyce said they opposed it. Jacques, who answered first, had the foresight to finesse the question — as she did throughout the debate. She moved deftly from the flag issue to noting that her father had been a Korean War veteran and a commander in the American Legion, which grounded her support for veterans’ benefits — including a law allowing veterans’ widows to retain their husbands’ exemptions from property taxes. Not to be outdone, Joyce answered the same question by working in a story about his father, a member of the "Greatest Generation" who had served in World War II. Throughout the debate, of course, both made lengthy references to their legislative achievements. And when asked by Keller, neither could think of even one regrettable professional mistake.

But both woke up to bad news in Sunday’s Boston Herald. A Herald/RKM Research and Communications poll of likely voters showed that Joyce and Jacques were splitting their base of progressive support, as many had feared: Joyce had the support of 18 percent of pro-choice voters, while Jacques had 15 percent. Incredibly, Lynch, who opposes abortion, got the nod from 29 percent of pro-choice voters. The poll also showed that the socially conservative Lynch was leading the race with 36 percent of the voters’ support. Joyce and Pacheco were tied for second with 12 percent, while Jacques had 10 percent. Twenty-nine percent of those polled remained undecided. Even before the poll came out, however, the whispering had already begun: There isn’t room for both Joyce and Jacques in the race. One of them has to get out.