MILWAUKEE – A new Marquette Law School Poll finds Hillary Clinton with 42 percent and Donald Trump with 35 percent support among Wisconsin registered voters in a presidential race matchup. Seventeen percent say they will vote for neither candidate. In the previous Marquette Law School Poll, in March, Clinton had 47 percent support and Trump 37 percent. Among likely voters, i.e., those who say they are certain they will vote in November, Clinton receives 46 percent to Trump’s 37 percent in the new poll, with 13 percent saying they will support neither candidate. While Clinton is the presumptive Democratic candidate, a head-to-head matchup between Democratic candidate Bernie Sanders and Trump finds Sanders leading 56 percent to 31 percent among registered voters and 57 percent to 33 percent among likely voters. In Wisconsin’s U.S. Senate race, among registered voters, Democratic candidate Russ Feingold is supported by 45 percent while Republican incumbent Sen. Ron Johnson receives 41 percent. In March, Feingold had 47 percent and Johnson 42 percent. Among likely voters in November’s election, Feingold has the support of 51 percent while Johnson is supported by 42 percent. Two percent say they will support neither and 5 percent say they don’t know whom they will support. Differences between registered and likely voters reflect shifting enthusiasm among Republicans and Democrats. In this new poll, 78 percent of Republicans say they are certain they will vote in November, a drop of 9 percentage points from the 87 percent who said so in March. Meanwhile, Democratic intentions to vote have increased, rising in June to 84 percent certain to vote from 81 percent in March. These shifts in likely-voter intentions account for the stronger support for Democrats in both presidential and senate races among likely voters than among all registered voters. By contrast, in June 2012, 90 percent of Republicans said they were certain to vote in November, as did 80 percent of Democrats. “The likelihood of voting reflects both personal involvement in politics and current campaign events,” said Charles Franklin, professor of law and public policy and director of the Marquette Law School Poll. “Studies have shown that this likelihood can fluctuate over the course of the campaign, only settling down as we move past Labor Day. However, the current data show the difficulty the Republican Party is currently facing with a sharp drop in enthusiasm for voting this November. After the national conventions in July, as both parties attempt to unify and rally their supporters, we will have a better idea how turnout will affect the election.” The poll was conducted June 9-12, 2016. The full sample includes 800 registered voters interviewed by cell phone or landline, with a margin of error of +/- 4.4 percentage points. Results for likely voters are based on 666 respondents with a margin of error of +/- 4.9 percentage points. Party unity and divisions Each party faces divisions left over from the primary season. Among Democrats and independents who lean Democratic, supporters of Sanders remain reluctant to vote…