The rate of the 25Al(p, γ)26Si reaction is one of the few key remaining nuclear uncertainties required for predicting the production of the cosmic γ-ray emitter 26Al in explosive burning in novae. This reaction rate is dominated by three key resonances (Jπ=0+, 1+ and 3+) in 26Si. Only the 3+ resonance strength has been directly constrained by experiment. A high resolution measurement of the 25Mg(d, p) reaction was used to determine spectroscopic factors for analog states in the mirror nucleus, 26Mg. A first spectroscopic factor value is reported for the 0+ state at 6.256 MeV, and a strict upper limit is set on the value for the 1+ state at 5.691 MeV, that is incompatible with an earlier (4He, 3He) study. These results are used to estimate proton partial widths, and resonance strengths of analog states in 26Si contributing to the 25Al(p, γ)26Si reaction rate in nova burning conditions.