The phrase "possible defection" means the likelihood or chance that someone may leave or abandon a group, an organization, or a team they were previously part of. Full definition
However, Piccoli thinks this option remains unlikely: «Despite some common ground, there are significant differences between them... A deal would entail significant risks for both Di Maio and (Lega leader Matteo) Salvini, including possible defections and a loss of popularity.» (cnbc.com)
While the House is far from vulnerable for Republicans, maintaining a strong majority allows for a stronger caucus and leeway for possible defections. (businessinsider.com)
Douglas Carswell faced a media scrum in the rain asking about further possible defections, the Rochester and Strood by - election, and TV leader debates for the 2015 general election. (bbc.com)