  We report on the first results of laser plasma wakefield acceleration driven
by ultrashort mid-infrared laser pulses (\lambda= 3.9 \mu m, 100 fs, 0.25 TW),
which enable near- and above-critical density interactions with
moderate-density gas jets. Relativistic electron acceleration up to ~12 MeV
occurs when the jet width exceeds the threshold scale length for relativistic
self-focusing. We present scaling trends in the accelerated beam profiles,
charge and spectra, which are supported by particle-in-cell simulations and
time-resolved images of the interaction. For similarly scaled conditions, we
observe significant increases in accelerated charge compared to previous
experiments with near-infrared (\lambda=800 nm) pulses.
