The Note: Obamacare central to midterm races The politics of health care has come full circle since 2010.

WASHINGTON --

The TAKE with Rick Klein

The campaign can be distracted by distortions and contradictions. Attention can and will be drawn to the Supreme Court, or to a migrant caravan and maybe briefly even toward a phantom tax cut.

But somehow races across the country keep coming back to one very big issue that's been galvanizing politics all decade: The politics of health care has come full circle since 2010.

With former President Barack Obama back on the campaign trail Friday, in Wisconsin and Michigan, it's striking to see how regularly his namesake law is item one in major races.

Sen. Claire McCaskill, D-Mo., is but one example of an incumbent whose re-election is pinned on the hope that voters will want to preserve protections for those with pre-existing conditions -- and that they will reject President Donald Trump's notion that Republicans are the ones who should be trusted to do so.

"Josh Hawley decided to go to court with your tax dollars and wipe out pre-existing conditions," McCaskill said of her opponent, the state's attorney general, at a debate Thursday.

Strategists in both parties recognize that days consumed by talking about health care -- the issue voters seem most inclined to talk about -- is a day Democrats are gaining ground.

The final 11 days before the midterms will take wild turns. Yet, from California to Maine, this is one topic that just won't go away.

The RUNDOWN with MaryAlice Parks

There is careful, and then there is decent and, say, presidential.

Sure, Trump was careful this week following the frightening news that explosive devices were sent to Democratic leaders across the country.

He did not name Democrats at his rally Wednesday and make them targets of personal and rowdy attacks as he usually does.

But he also did not name them at all. He spoke only generally about being worried. White House staff dodged all questions about whether the president bothered to personally call his targeted predecessor.

Since taking office, Trump has struggled to show those Americans who prefer the other political party that he has their backs, too, and this week felt like more of the same on that front, despite the careful words.

The TIP with John Verhovek

2016 was the year the blue wall fell.

Wisconsin, Michigan and Pennsylvania were the states that propelled Trump to the presidency, and now his predecessor is back, in the final weeks of the midterm campaign, to try to re-take what was once solidly Democratic territory.

Obama's campaign swing Friday through Wisconsin and Michigan is meant to boost Democratic Senate and gubernatorial candidates, but it's also about reclaiming a key geographical part of the party's electoral coalition.

"The last presidential election turned on fewer than 100,000 votes in three states. More people go to Coachella," Obama tweeted, urging people to get to the polls.

For a president often maligned for allowing state-party infrastructure to falter during his time in office, making amends can start with 2018 victories in Midwest battlegrounds.

THE PLAYLIST

ABC News' "Start Here" Podcast. Friday morning's episode features ABC News' Deborah Roberts, who is on the ground in Georgia getting a sense of the governor's race, which Democrats eye as a key pickup opportunity. And former Acting Under Secretary of Homeland Security and ABC News contributor John Cohen tells us about the New York Times report that China is listening in on Trump's cell phone calls. He said China would be interested to hear Trump's feelings on trade negotiations. https://bit.ly/2M7OS5c

FiveThirtyEight’s Politics Podcast: The Campaign Ads Dominating 2018. In this episode of the FiveThirtyEight Politics podcast, the crew looks at the most featured topics in campaign ads in order to understand what the parties are prioritizing. Compared with the past two midterm cycles, Democrats are on the attack on health care while Republicans are playing defense. https://53eig.ht/2RbzZwC

WHAT YOU NEED TO KNOW TODAY

Trump delivers remarks at the 2018 Young Black Leadership Summit at the White House at 11:45 a.m. The president then heads to Charlotte, N.C., for a "Make America Great Again" rally at 7 p.m. EDT.

ABC News White House Correspondent Tara Palmeri interviews Vice President Mike Pence in Roswell, New Mexico, as he campaigns for congressional candidates around the issue of border security.

Homeland Security Secretary Kirstjen M. Nielsen travels to Calexico, California, to view the first completed section of Trump's 30-foot border wall in the El Centro Sector. Nielsen also holds a new conference on securing the nation's borders at 12 p.m. EDT.

Former congresswoman Gabby Giffords, a survivor of gun violence, hosts a roundtable discussion with other gun-violence survivors, student leaders and Giffords-backed candidates at the University of Minnesota at 11:30 a.m. EDT. Comedy Central host Jordan Klepper and students from March for Our Lives then join Giffords to hold a "Get Out the Vote" town hall on campus at 3:30 p.m. EDT.

Attorney General Jeff Sessions hosts a forum on combating wildlife poaching and trafficking at the Justice Department at 10 a.m. Health and Human Services Secretary Alex Azar delivers the keynote address at the University of Southern California Brookings Schaeffer Initiative for Health Policy at 8:45 a.m. EDT.

This Week on "This Week": With less than two weeks until the midterms, the Powerhouse Roundtable debates the week in politics, with ABC News Political Analyst Matthew Dowd, New York Times Chief White House Correspondent Peter Baker, co-author of “Impeachment: An American History," Washington Post National Correspondent Mary Jordan, and National Review Executive Editor Reihan Salam, author of “Melting Pot or Civil War?: A Son of Immigrants Makes the Case Against Open Borders."