Democrats look at packing the Supreme Court to pack the vote Joan Biskupic, CNN Digital Expansion 2018

Washington (CNN)- Republicans have been successfully leveraging the Supreme Court balance of power as a major campaign issue to ignite their base since the 1980s. For Democrats, the 2020 election may mark the first in modern times that they unite around the high court as a driving force in a presidential election.

Democratic candidates are increasingly advocating "court packing," that is, upping the number of Supreme Court justices to balance the bench -- or ensure a liberal majority. The idea is unlikely to succeed for historical and practical reasons but its resonance on the campaign trail reflects Democrats' new emphasis on the judiciary during the Trump era.

The issue emerges partly from lingering anger over the Republican-led Senate's 2016 stall of President Barack Obama's nominee Merrick Garland, a fire stoked this week when Senate Majority Leader Mitch McConnell said if a Supreme Court vacancy occurred in 2020 election year, he would confirm a Trump nominee.

McConnell's comments were an audacious reversal of his 2016 election-year position blocking Garland for the vacancy caused by the sudden death that February of Justice Antonin Scalia. McConnell argued that the seat should be filled by whoever won the then-upcoming presidential election.