Actually the last time was in 2012 when the Republicans were making a case that if the electors were done based on congressional districts rather than states, Romney would have won 2012. And they are correct as far as it goes — the rub being that the campaigns would have been run differently in that case so it is impossile to say for certain a vote would have gone the other way. Note that under such a system, Bush would still have beaten Gore, but he would have had a larger margin.
For but one example of the history on this check out http://www.huffingtonpost.com/2013/01/24/republican-vote-rigging-electoral-college_n_2546010.html
Clearly they were not successful, and clearly they wanted to change it in a way suiting them (just as Democrats want to change it in a way suiting their party) but to say they didn’t try is inaccurate.