A great review of this subject comes from a really interesting article at Election Law Blog by Derek Muller. Here is an extract:

I’ve chronicled how the 2015 “Cromnibus” bill appears to have contributed to a sharp increase in spending on election litigation. The bill allowed additional contributions to “election recounts and contests and other legal proceedings,” above and beyond individual candidate campaign contribution limits. Essentially, it’s easier to give much more money directly to the party’s lawyers than to the party’s presidential candidate.

The staggering numbers continue to climb. In the 2019-2020 election cycle–a presidential election–the totals to the major national party accounts crossed $117 million. The 24-month figures are in for 2021-2022, and they’re up 30%, to $154 million.

DNC: $42,882,652

RNC: $18,711,921

Continue reading here.