BOSTON (CBS) – Sen. Ed Markey and his Democratic primary challenger, Rep. Joe Kennedy have already had their first televised debate. There are four more to come before the September first primary, including a showdown at WBZ-TV on August 11th. And among those who watched the first one, the two candidates are in a virtual tie.

But our exclusive Suffolk University/WBZ-TV/Boston Globe poll finds Kennedy in the lead by six points, just outside the survey’s 4.4 percent margin of error.

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Polls taken last fall when Kennedy jumped in may have given him a big lead, but as this race comes into focus, so are some of Markey’s political strengths.

(WBZ-TV Graphic)

Fifty-three percent of those polled rate Markey’s performance in office good or excellent. Just under 50 percent say he deserves to be re-elected.

For an incumbent these days, those aren’t bad numbers.

Nonetheless, this poll shows the challenger holding the upper hand in key areas.

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Kennedy leads among voters 18 to 55, none of them old enough to remember the political heyday of his famous relatives (although a sizeable percent of them remain undecided).

And in a party where taking on President Trump is considered job one, Kennedy is seen by nearly a two-to-one margin as a better Trump adversary than Markey.

The two men are in a virtual tie among liberals, but Kennedy cleans up with moderates by a 48 to 31 percent spread. And in a pre-Labor day primary where getting your voters out will be make or break, Kennedy’s 15 point advantage among usually high-turnout union members is a positive leading indicator.

So, too, is the geographical turnout advantage Kennedy will enjoy by virtue of giving up his House seat. “In the southeastern Mass/Cape region, Kennedy up by 31 points,” notes Dave Paleologos, director of the Suffolk University Political Research Center. “Markey winning in Middlesex and Essex counties is a nice thing, but it doesn’t offset Kennedy’s geographical advantage. Geography is gonna trump any of the other demographics.”

Not to mention the generational geography of this matchup.

When you have a 39-year-old challenger taking on a 73-year-old incumbent, the generational contrast is going to be front and center. It’ll be up to Ed Markey to find a way to make that work for him or at least neutralize it.

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For more discussion of this poll, Saturday’s Suffolk/WBZ/Globe poll of the Massachusetts presidential primary, and analysis of the Super Tuesday results, stream CBSN Boston from 8-10 p.m. Tuesday night March 3, with coverage switching to TV38 at 10 p.m. and WBZ News at 11 p.m.

Jon Keller