— -- Some Americans are considering not casting a vote for president in this year's election in what they say would be an act of conscience.
Jake Shockley, 22, is one of them.
Unsatisfied with the presidential candidates, Shockley said he may not vote for any of them while casting a ballot in other races.
"If I were to follow the rhetoric of voting for the least of the two evils, I would probably vote for [Donald] Trump," Shockley, a senior at Missouri State University who favored Republican Ben Carson in the primaries and voted for Democrat Barack Obama in 2012, told ABC News in a phone interview. "But since I do not believe in voting for the lesser of the two evils, I’m choosing not to."
A recent Pew Research Center study found that many voters are motivated to head to the polls out of their dislike for one particular presidential candidate: 33 percent of supporters of Republican hopeful Donald Trump and 32 percent of those backing his Democratic rival Hillary Clinton attribute their choice to opposition to the other nominee rather than enthusiasm for their candidate.
But high unfavorable ratings for both Trump and Clinton may also mean that a number of people, like Shockley, will choose to leave the presidential section of the ballot blank.
David Kochel, a veteran Republican strategist who has advised both Jeb Bush and Mitt Romney in their presidential bids, says abstaining from voting for president this year is a "totally valid" option and one he’s considering himself.
"I've been working for Republican candidates for 32 years. I have voted in almost every election unless there was some specific reason why I couldn’t," Kochel told ABC News. "If in this one case, where you have a line on the ballot where neither of the choices of the major parties is acceptable, I think it’s a perfectly legitimate way to express dissatisfaction with both nominees."
His advice to other dissatisfied voters in 2016 is to vote their conscience.
"Imagine if 20 million people in the country decided to vote for the down-ballot races but just decided they’d had enough of the presidential election and not vote for the top of the ticket?" Kochel pondered. "That would send a very powerful signal. You’ve got to vote your conscience."
Even some members of Congress, such as Republican Rep. Mike Coffman of Colorado, are contemplating the no-vote option.
"I’m struggling with it like many Americans," Coffman said of the question of who to back for president in an interview with a Colorado NBC affiliate station.
"I don’t know if I’ll cast a vote for president," said the congressman, who represents a swing district outside Denver with a large Hispanic community and who has aggressively distanced himself from Trump in 2016.
At least one former presidential candidate may have found a creative way to express his conscience on this year's ballot.
Sen. John McCain, the Republican nominee in 2008 who is running this year for reelection as an Arizona senator, revealed earlier this month that he may write in his choice for president -- his friend and former 2016 Republican presidential candidate, South Carolina Sen. Lindsey Graham.
ABC News Ben Siegel contributed reporting.