Supporters of Proposition 29 say additional cigarette taxes help people quit. (Sean Gallup/Getty Images)

The big battle in the June 5 primary is Proposition 29, which would raise the tobacco tax to pay for cancer research. Ads are all over the airwaves, particularly from the measure’s opponents. And the Field Poll suggests they may be having some effect: the measure holds a 50-42 percent lead among likely voters. But among Californians who plan to vote at their polling place on Election Day, it only has a five-point lead. Those are voters who have not cast their ballots yet, and the advertising could be leading to the drop in support.

The other measure is Proposition 28, which would reduce the overall number of years state lawmakers can serve, but would let them spend the entire time in either the Senate or the Assembly. That initiative holds a much wider lead, 50 percent favoring to 28 percent opposed. Nearly a quarter of those polled say they’re undecided.