Election results Tracker

CBS News

By Anthony Salvanto, Fred Backus, Jennifer De Pinto, Sarah Dutton

Showing no signs of a slowdown heading into the fall, Donald Trump leads the Republican Presidential field in each of the early voting states of Iowa, New Hampshire and South Carolina. Trump's lead in New Hampshire is especially large and he's up double-digits in South Carolina. In Iowa, it's become a two-man field for the moment, as Dr. Ben Carson is closer to Trump than anyone in any state, and together the two political newcomers have distanced themselves from the rest of the pack.

While he leads, very few of the voters backing other candidates pick Trump as their second choice: just one in ten of them do. So together that forms a picture of the field where Trump is a known commodity and voters are either with him or not. Ben Carson, on the other hand, gets the largest percent for second-choice in all states, suggesting that he could be positioned to move up further.

The CBS News 2016 Battleground Tracker is based on interviews conducted on the internet between September 3 and 10 with 4, 860 registered voters in Iowa, New Hampshire, and South Carolina. The poll was conducted by YouGov, an online polling organization. The "margin of error" is an approximate 95 percent confidence interval for the sampling proportion.

Respondents were selected for participation from available panel members to be representative of registered voters from each state in terms of age, race, and gender. A propensity score (based upon a case-control logistic regression including age, race, gender, education, born-again status, and party registration) was estimated for each respondent and responding panelists were post-stratified upon propensity score deciles. A score for likelihood of voting was computed for each respondent based upon past turnout and self-reported likelihood of voting in the presidential primary.

Respondents were selected from YouGov's and two other online panels and YouGov also randomly selected persons from voter registration lists who had previously voted in primary elections and contacted them by phone. A total of 19, 047 registered voters were contacted by phone and the YouGov sample includes 1, 163 phone recruits. A complete description of the methodology is in the link below.