2028 Republican primary forecast

Chance of winning the nomination without jd vance; 5,000 simulated races

Candidate	Poll average	Chance of the nomination	Delegates, average	Wins Iowa	Wins New Hampshire
Marco Rubio	20.1%	47%	1,108	40%	42%
Ron DeSantis	7.2%	19%	450	19%	19%
Donald Trump Jr.	6.9%	18%	436	18%	19%
Ted Cruz	3.1%	7%	185	10%	8%
Robert F. Kennedy Jr.	2.4%	5%	140	8%	7%
Nikki Haley	1.9%	4%	110	6%	5%

Poll average: each pollster's latest national Republican primary poll in the 120 days to 19 October 2026 (13 polls), as polled; the model shares out the undecided and anyone left out of the field. No one reaches the 1,215 pledged delegates needed in 5% of simulations: a contested convention, counted here for whoever holds the most delegates.

The first contests

• Iowa 17 Jan 2028 · caucus · 40 delegates
  1. Marco Rubio 40%
  2. Ron DeSantis 19%
  3. Donald Trump Jr. 18%
• New Hampshire 25 Jan 2028 · primary · 22 delegates
  1. Marco Rubio 42%
  2. Donald Trump Jr. 19%
  3. Ron DeSantis 19%
• Nevada 10 Feb 2028 · caucus · 26 delegates
  1. Marco Rubio 42%
  2. Ron DeSantis 20%
  3. Donald Trump Jr. 18%
• South Carolina 26 Feb 2028 · primary · 50 delegates
  1. Marco Rubio 44%
  2. Ron DeSantis 18%
  3. Donald Trump Jr. 17%
• Michigan 29 Feb 2028 · primary · 55 delegates
  1. Marco Rubio 45%
  2. Ron DeSantis 19%
  3. Donald Trump Jr. 18%
• Idaho 4 Mar 2028 · caucus · 32 delegates
  1. Marco Rubio 45%
  2. Ron DeSantis 19%
  3. Donald Trump Jr. 18%

The Republican early order as the RNC approved it in September 2026: Iowa, New Hampshire, Nevada, South Carolina; their 2028 dates are not set, so we use 2024's moved to the same weekday. Other states' dates, delegates and allocation rules are 2024's until the 2028 ones are set.

How it works, and how well it has done

• The start. Each candidate's share in the national primary polls, among the field shown. How far that support can move before voting starts depends on the time left: measured on past races, it is wide a year or more out, so the chances stay spread out.
• State by state. Each state votes in calendar order with its own variation from the national picture (more at caucuses and in the first three contests), and a candidate's home state lifts them.
• Momentum and dropouts. Winning an early contest lifts a candidate's national support, most for those who started small; the others slip. Candidates far behind drop out, as they do in real races.
• Delegates. Republicans use each state's own rule: winner-take-all, winner-take-all above a share, or proportional above a threshold. The nominee is whoever wins a majority.
• The test. We ran the model on the open nomination races of 2004 to 2020, each time leaving that race out of the fitting. Before any votes it gave the eventual nominee 35 to 39% on average, a little better than taking poll shares as chances (30 to 36%); the poll leader a month before Iowa won 3 of 7. Started after the first eight dates, with the delegates already won, it gave the nominee 78% on average. Adding money raised (FEC filings) made the early forecast worse, so it is left out.
• Limits. A year and more before voting starts we widen the uncertainty beyond what the test covered. Primary polls miss far more than general-election polls, about 8 points on average since 2000. Nobody has declared, so who runs matters more than anything here: where a candidate has made running depend on someone else (Newsom has said he will not run if Harris does), we show both fields.