CLINTON — Good morning from Iowa, where the campaigns have entered the final wind sprint to the finish line. As Donald J. Trump returns to the state, joining nine other Republicans and all three Democrats, campaign operatives and the news media will be anticipating one thing more than any rally: the release at 5:45 p.m. Central time of J. Ann Selzer’s final Iowa Poll.  Ms. Selzer, who has polled for The Des Moines Register for decades, is highly regarded for the accuracy of her surveys. She correctly predicted Barack Obama’s surge in the 2008 caucuses, when she identified an astonishing 60 percent of likely Democrats who had never caucused before. She has also come close to pinpointing the winning margin in other races that a majority of her profession missed.  The results will be released at a news conference in a studio set up by Bloomberg Politics in the Des Moines Marriott, the de facto caucus headquarters for the media.  One number many people will scrutinize: Marco Rubio’s, to see whether he is closing in on Mr. Trump and Ted Cruz in a late surge. The history of the caucuses is full of volatility in the last week, and Mr. Rubio, after only flirting with Iowans for much of the past year, has become an aggressive paramour.  His strategy mirrors that of another late-arriving suitor in Iowa four years ago who ended up exceeding expectations: Mitt Romney.  From Kid Rock’s “Born Free” — a Romney standard that blared at a Rubio rally in Clinton on Friday — to Mr. Rubio’s heavy focus on eastern Iowa in the closing days, the Florida senator is reading right out of the Romney playbook for establishment-oriented Republicans.  Mr. Romney, who finished second in 2012 by only a handful of votes, carried just 16 of Iowa’s 99 counties. But he won population centers, primarily in eastern Iowa. On Friday, Mr. Rubio visited the Mississippi River cities of Burlington, Dubuque and Muscatine. After a jog to western Iowa on Saturday, he returns east for his final push on Sunday in Cedar Rapids and Davenport, the second- and third-largest Iowa cities.  Not coincidentally, Mr. Rubio’s campaign is saturating the Cedar Rapids media market.  “We feel this part of the state is very strong for us,” State Senator Jack Whitver, Mr. Rubio’s state chairman, told me at a rally in Clinton. “This congressional district is a swing district. People keep an open mind.”  Two men waiting in line to shake Mr. Rubio’s hand in Clinton, Bob Carlson, a physician, and Steve Teney, a community college professor, both caucused for Mr. Romney in 2012 and plan to do so for Mr. Rubio.  “The main reason I picked him,” Dr. Carlson said, “was he seemed like he’d win in the general election, and that’s one of the biggest selling points of this guy.”  Trip Gabriel, a 21-year veteran of The New York Times, has lived in Iowa for the past year, covering the state’s unique role in presidential politics. Mr. Gabriel, previously known for his invention of the Modern Love column at The Times, has been recognized for his expertise on Iowa’s intricate caucus system. He lives in Des Moines and has a regular seat at Eatery A, the pizza parlor that once served as campaign offices for Barack Obama, and later for Mitt Romney._____  Find out what you need to know about the 2016 presidential race today, and get politics news updates via Facebook, Twitter and the First Draft newsletter.
We sent our reporter Trip Gabriel to live in Iowa. Here’s what he’s watching for as the caucuses near.