Photo

Good Tuesday morning. The day before the second Republican debate, campaigns are honing their strategies, Twitter is looking at donations, and polls are rearranging the numbers and the leader board. As big names fall, and Donald J. Trump sees only a modest gain, Ben Carson no longer has to look ahead to see who is leading in polls: He can just look to his side.

Mr. Carson has amassed considerable new support from Republican primary and caucus voters and is now running nearly even with Mr. Trump as their pick for the party’s presidential nomination, according to a new New York Times/CBS News poll.

Far more than other Republican contenders, Mr. Carson, a retired neurosurgeon, has capitalized on his outsider message — a mix of anti-establishment views, delivered in a calmer tone than Mr. Trump’s, and socially conservative positions — to draw voters away from rivals and leap ahead in the poll, which will be published on Tuesday. The proportion of Republican voters favoring Mr. Carson rose to 23 percent from 6 percent in the previous CBS News poll, which was taken just before the first televised Republican debate in early August. Over that same period, Mr. Trump made modest gains, to 27 percent from 24 percent.

Mr. Carson pulled at least some of his support from Republicans who are more typical political figures. Jeb Bush fell in the poll, to 6 percent, from 13 percent, and Gov. Scott Walker of Wisconsin tumbled to 2 percent from 10 percent. No other candidates fell as much as those two, according to the poll. Mr. Carson drew more support from college graduates than Mr. Trump, while those without a college education were more likely to favor Mr. Trump.

Over all, 37 percent of Republican voters say their minds are made up about which candidate they will support as their party’s presidential nominee, while 63 percent say it is still too early to say. Slightly more than half of Mr. Trump’s backers say they have decided, while 46 percent said they could still switch candidates. Those who said they had made up their minds are twice as likely to support Mr. Trump over Mr. Carson. Women were less likely than men to support Mr. Trump and more likely than men to support Senator Marco Rubio of Florida.

The only other significant gain was made by the third outsider in the Republican field, Carly Fiorina, the former chief executive of Hewlett-Packard, who drew support from 4 percent of voters, compared with a trace amount in midsummer.

The New York Times/CBS News poll was conducted from Sept. 9 to 13 and has a margin of sampling error of plus or minus six percentage points for Republican primary voters. Additional findings from the full poll will be released on Tuesday evening, a day before the next Republican presidential debate.

— Patrick Healy

What We’re Watching Today

– The Republican candidates are hunkering down for the most part before the debate, but Jeb Bush will attend a fund-raiser and a technology round table in California.

–President Obama will host King Felipe VI and Queen Letizia of Spain at the White House, while in the evening, Vice President Joseph R. Biden Jr. and his wife, Jill Biden, will host an event for Hispanic Heritage Month at the Naval Observatory.

– And Mr. Obama’s top climate change negotiator will meet with his Chinese counterpart in Los Angeles on Tuesday to announce joint actions in both countries to reduce greenhouse gas emissions.

Our Favorites From The Times

Democrats Lay Groundwork to Expand Use of ‘Super PACs’ A request filed with the Federal Election Commission asks to employ tactics Republican presidential candidates have pioneered, and could force a ruling on their legality.

Showdown Between Carly Fiorina and Donald Trump Expected at Republican Debate Political strategists warn male candidates to use caution when debating against a female rival. But it remains to be seen if Mr. Trump will take that approach on Wednesday.

Bernie Sanders Makes Rare Appeal to Evangelicals at Liberty University Senator Bernie Sanders, in a speech at Liberty University, an evangelical Christian college, repeatedly sought to build what he called “common ground” with students, beginning with the foundations of Christianity itself: the Bible.

What We’re Reading Elsewhere

– A Washington Post-ABC News Poll shows Hillary Rodham Clinton with a drastic loss of support among Democratic women, which The Post says “suggests that the historic significance of Clinton’s campaign, which holds the prospect of electing the nation’s first female president, is being overtaken by other forces.”

– In an interview with Extra, Mrs. Clinton said that though she was watching Mr. Trump’s success in the campaign “with some concern,” she was “certainly looking forward, if he were the nominee, to debating him in the general election because there’s a lot to talk about.”

– And The New Yorker says that recent fascination with the tops of the heads of Mr. Trump, Mrs. Clinton and Senator Bernie Sanders of Vermont reflects that “Americans love to talk about hairdos.”