Todd Purdum: “It’s the predominant paradox of contemporary American politics: If Republicans prevail in this year’s midterm congressional elections, it will be because of their party’s sharp-edged stances on topics like abortion and Benghazi, Obamacare and immigration, gay marriage and the minimum wage — issues that energize the GOP’s core base of support.”

“But if Republicans lose the race for the White House in 2016, it will be because of their party’s polarizing, out-of-step stances on those very same issues, which alienate much of the broader electorate the GOP needs to win a national contest in a country whose demographics and political realities are shifting under its feet.”

“With Tuesday’s primaries reinforcing the strength of the Republican establishment, House Democrats are reassessing their electoral strategy based on a major internal research project that shows their candidates stand a better chance when they portray Republicans as uncaring toward working-class Americans while they continue to back policies favoring the wealthy and corporate America,” the New York Times reports.

“Democrats could build on this distrust, the research showed, by emphasizing support for policies such as equal pay for men and women, ensuring that corporations pay a fair share of taxes, and increased job opportunities in the United States.”

A new WBUR survey in Massachusetts finds Martha Coakley (D) is leading Steve Grossman (D) the Democratic gubernatorial primary, 51% to 7%.

In a possible general election match up, Coakley tops Republican frontrunner Charlie Baker (R), 39% to 30%.

“Republican voters who cast their ballots in the last days of Oregon’s primary — following news stories about Monica Wehby’s (R) ‘stalking’ incident — were less likely to support her in Oregon’s GOP Senate primary,” the Oregonian reports.

A new Siena College poll finds Rep. Charlie Rangel (D) leads primary challenger Adriano Espaillat (D), 41% to 32%.

The Upshot now gives Democrats a 57% chance of retaining control of the U.S. Senate.

A new Marquette Law School Poll finds that the Wisconsin governor’s race has tightened to a dead heat, with Gov. Scott Walker (R) and challenger Mary Burke (D) each receiving the support of 46% of registered voters, while 6% are undecided.

“Turnout in the fall election is likely to play an important role. While the race is tied among all registered voters, among likely voters–those who say they are absolutely certain to vote in November–Walker receives 48% to Burke’s 45%, which is inside the +/-3.5 percentage point margin of error for the poll.”

A new Public Policy Polling survey in Iowa finds Joni Ernst (R) leading the Republican U.S. Senate primary field with 34%, followed by Mark Jacobs (R) at 18%, Sam Clovis (R) at 14% and Mark Whitaker (R) at 6%.

Senate Minority Leader Mitch McConnell (R-KY), “fresh off his primary win against challenger Matt Bevin, is challenging Democratic nominee Alison Lundergan Grimes to three debates,” Sam Youngman reports.

The invitation: “In order to present our views fairly and without interpretation by traditional media filters, I believe we should participate in three traditional Lincoln-Douglas style debates moderated only by a single timekeeper/moderator. By conducting these debates without an audience, without props and without notes, it will allow for an unvarnished exchange of views for Kentuckians to evaluate.”

Nate Cohn: “In the racially polarized South, where white voters have been trending Republican for more than a generation, the Democratic route to 50% is mainly a matter of racial demographics. Democrats must wait for more nonwhite voters to overcome their disadvantage with white voters.”

“That wait might end soon in Georgia, but not in this November’s election. In the midterm balloting, the share of whites will be around 64% of registered voters, down from 72% in 2002, when the Democratic senator Max Cleland lost re-election by 7 points. Ms. Nunn will need nearly 30% of white voters to prevail. If Mr. Cleland were running today, his 30 or 31% of white voters would probably be enough to squeak out a win.”

“But most Democrats running for federal office in Georgia fall well short of that 30%… The difference between 26 and 30% of white voters might not seem like much, but it is very significant in the South. It is even harder for Democrats to reach 30% of Georgia’s white voters today than it was in 2002.”