Labour has a lead over the Conservatives today, a 95 percent probability of winning an absolute majority in the House of Commons at the next general election; however, it is too good to last. On past form the gap in public opinion between Labour and the Conservative government will begin to narrow as the election approaches. Rishi Sunak's ambition is to push the chances of the Conservatives coming first from 1 in 100 to better than one in five.
As long as a landslide Labour victory is in sight, left-of-centre voters can cast a ballot for the party that best reflects their political view with no risk of "wasting" their chance to vote for or against the return of a Conservative government. The Green Party claims 4.6 percent of respondents in this January's public opinion polls, up from the 2.7 percent it won at the 2019 election. However, it is far from what the Greens need to exert influence on the formation of a government, for it has only one MP and no prospect of gaining more.
Once Labour begins to lose support as voters who have currently switched to Labour from the Tories return to their home base, Sir Keir Starmer will be looking for fresh support to ensure a Labour government. The opportunity to gain fresh support is as plain as grass in every conventional Conservative constituency: it is to attract support from voters who currently favour the Greens.
At this point Sir Keir Starmer can pitch for Green supporters to vote Labour to turn the Conservative government out. The appeal for tactical support can be re-enforced by calling attention to the pro-environment policies that Labour endorses. A social media appeal could be captioned: Vote Red to Go Green.
Even though there is a low ceiling on the number of votes that Labour can claim from Green defectors, when combined with a significant swing to Labour it would be enough to deliver some seats to Labour. The number would depend on what proportion of current Green supporters would switch to Labour.
If there was a swing back of five percentage points from Labour to the Conservatives that would cut Labour's likely number of seats from 450 to 350. The media headlines would read 'Labour threatened with loss of majority', for it would be within 25 seats of doing so. This would remind Green supporters that by maintaining their position they risk losing the chance of Labour replacing the Tories.
If half of the current 4.6 percent that say they are Green voters switched to Labour to keep the Tories out and the rest remained Green or abstained, this would add 15 MPs to Labour's total in the House of Commons. If media headlines convinced 4.6 percent (nearly all the Greens plus a few who said they were don't knows or Nationalist) to back Labour, then the party could win 40 additional seats. The new recruits from the Greens would have the satisfaction of turning the Tories out and and having five years to see whether Labour justified their second-best choice or revert to the Greens in 2029.
Richard Rose is Britain's senior psephologist and an expert on party government. His new book 'How Sick is British Democracy?: a Clinical Analysis' is published by Palgrave.