The opposition's large polling lead had evaporated.
Bush subsequently lost around five points of his polling lead.
Even last August, Zac Goldsmith had a substantial polling lead over Khan.
Mr. Romney lost 15 points off his national polling lead in the Gallup national tracking poll over this period.
In 6 of the 11 years in our study, the challenging party held the polling lead before the conventions, although it was modest in most of these cases.
If Mr. Rubio can maintain the polling lead until the 2014 midterms, history would suggest that he will very likely run in 2016.
If a polling lead in the first week of September were a guarantee of victory two months later, then John McCain and Al Gore would have both been sworn in as president of the United States.
By about the same margin they like its talk of tackling dodgy landlords, blocking foreign takeovers of British firms and boosting the minimum wage.Yet Labour's polling lead over the Conservative Party is slipping.
Even after Mr. Kennedy lost his national polling lead, both Iowa and New Hampshire represented good opportunities — in Iowa because its caucuses are dominated by relatively liberal Democratic activists, and in New Hampshire because Mr. Kennedy was from neighboring Massachusetts.
Its polling lead over the Conservatives has slipped from a modest six points at the start of the year to one or even zero points now (four recent YouGov polls have put the two parties neck-and-neck).
"Today is a reminder that you can't take the recovery for granted," warned George Osborne, who knows that one weak GDP number is unlikely to dent his polling lead on economic competence.
