3000 votes in Michigan which was under 1% and was a tie with Romney till the rules committee voted to change the rules in the middle of the night.
However Gingrich didn’t interfere in Michigan but getting out would have cost Romney the state and likely ended his run.
His withdrawal and endorsement of Santorum after Colorado/Minnesota/Missouri would have ensured that Romney lost the nomination.
It was at this point - his candidacy had no hope. He had been superceded by Santorum’s campaign. Instead, he stayed in, conservatives were split and the result is what we had today.
People here were warning you folks about these things. Why did you not all listen to them?