The Note: Parties turn to bases as potential split decision looms Talk of waves might be missing the meteorological mark.

WASHINGTON --

The TAKE with Rick Klein

Talk of waves might be missing the meteorological mark.

There's a new metaphor making the rounds among party strategists. Instead of a wave, where all the close races tip in one direction, the 2018 midterms could be a series of tornadoes -- chewing up portions of the map, but leaving others unharmed.

That leaves the very real -- and right now the likeliest -- scenario of a split decision. FiveThirtyEight is forecasting a 6 in 7 chance for Democrats to win the House, and a 7 in 9 chance for Republicans to hold the Senate.

This landscape in part explains the base-driven strategy both Democrats and Republicans will be deploying this week. Former President Barack Obama is in Nevada on Monday, two days after President Donald Trump. Trump will hit Wisconsin on Wednesday, while Obama will be there two days later.

In Texas, meanwhile, Republicans are seeking to combat Betomania with a once-unthinkable event Monday evening in Houston. Trump and Sen. Ted Cruz will share a stage -- needing each other, and their shared base of voters, more than ever.

The RUNDOWN with MaryAlice Parks

Sen. Ted Cruz has capitulated.

During an interview with ABC's Paula Faris, the president's former primary rival said he has "no interest in revisiting the comments of 2016," when he called Trump "utterly amoral," "a serial philanderer" and a "pathological liar."

Despite their complicated relationship, Trump will campaign side-by-side next to Cruz Monday in Houston.

Faris asked Cruz if he would consider Trump a friend or a foe, and the senator stopped short, saying, "He's the president. I work with the president in delivering on our promises."

The new, courted relationship with the commander in chief is risky.

Yes, playing nice to the head of the party and reinforcing the base vote could help Cruz, who is in an unexpectedly tough fight against Democratic Rep. Beto O'Rourke this year for his Senate seat.

On the other hand, the president was never overwhelmingly popular in the otherwise traditionally red Lone Star State.

And on immigration, the hardest line could look utterly impractical to many Texans.

Cruz, for example, said he supports Trump's comments on a possible militarization of the border, but disagreed with him on reinstating family separation.

The TIP with John Verhovek

Iowa Rep. Steve King has made controversy throughout his career, and that doesn't seem to be changing anytime soon.

In an interview with ABC News on Sunday, the Republican incumbent, facing a well-funded and aggressive Democratic challenger this cycle, doubled-down on his decision to endorse a candidate in the Toronto mayoral race that holds white nationalist views, saying that she is a "clear voice for western civilization, for Christianity and for the rule of law."

King, running for a ninth term in Congress, said the criticism of his endorsement is overblown, and claimed the left is using the word "Nazi" to smear their political opponents.

"I could not name for you anyone that I have seen the evidence that they are a Nazi -- I didn't think a single one existed anywhere until they roll out this adjective," King told ABC News at a local Republican Party event in Boone, Iowa. "Now it seems like they're everywhere. They're about as replete in our society as the racists were before they wore the name out."

When asked about her appearance on a podcast hosted by the organizers of the 2017 white nationalist rally in Charlottesville, Virginia, King did not seem deterred.

"Those are some of the names they've called me for a long time," King said. "I probably couldn't read the Declaration of Independence on the floor of the House of Representatives without offending the left."

THE PLAYLIST

ABC News' "Start Here" Podcast. Monday morning’s episode features a conversation with ABC News Senior National correspondent Paula Faris, who tells us about her interviews with Texas Senate candidates Beto O'Rourke and Ted Cruz. And, ABC News' Rym Momtaz says the Saudi explanation for Jamal Khashoggi's death is changing.

WHAT YOU NEED TO KNOW TODAY

-- President Donald Trump holds a Make America Great Again rally in Houston with Texas Republican Sen. Ted Cruz at 7:30 p.m. EDT. This is the president's second campaign rally in the Houston area since he first began his presidential race in June 2015.

-- Barack Obama headlines a rally in Las Vegas at 4 p.m. EDT for Democratic candidates including Rep. Jacky Rosen, who is running against Republican incumbent Sen. Dean Heller.

-- Former Vice President Joe Biden, joined by Sen. Bill Nelson, kicks off his two-day campaign for Florida Democrats with a rally in Tampa, Florida, at noon. After that, Biden will headline a second rally in Jacksonville, Florida, at 3:45 p.m.

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The Note is a daily ABC News feature that highlights political analysis of the day ahead. Please check back Tuesday for the latest.