It could be an organ, but I think it’s a synth. Try this:
Osc 1: Saw wave, 5-voice unison with narrow width and enough detune to really smear it.
Osc 2: Same as Osc 1, but one octave higher.
Filter: 12dB Lowpass. Set the cutoff somewhere in the middle and modulate it with…
LFO: Triangle or Sine wave, at a fast 16th note rate. A modest amount. You’ll have to tinker with the mod amount and cutoff to get it just right.
Phaser: Just a light bit of it to create the subtle sweeping filter-ish sound.