Romney had won 270 delegates in through the Super Tuesday contests, compared with front-runner John McCain's 680.
Romney had no public events Wednesday and instead met with aides to discuss strategy to stay in the race through March 4.
"It is tough to saddle up this a.m.," one Romney adviser told CNN the morning after his disappointing Super Tuesday finish.
Although he outspent his rivals, Romney received just 175 delegates on Super Tuesday, compared with at least 504 for McCain and 141 for former Arkansas Gov. Mike Huckabee, according to CNN estimates.
Romney came in first in Massachusetts, Alaska, Minnesota, Colorado and Utah on Super Tuesday. In the early voting contests, he won Nevada, Maine, Michigan and Wyoming.
After his win in the first-in-the-nation Iowa caucuses, former Arkansas Gov. Mike Huckabee became Romney's chief rival for the party's conservative vote.
Huckabee on Tuesday won Arkansas, Tennessee, Georgia, Alabama and West Virginia.
Suspending a campaign has a different meaning depending on the party.
On the Republican side, decisions on how to allocate delegates is left to the state parties.
On the Democratic side, a candidate who "suspends" is technically still a candidate so he or she keeps both district and statewide delegates won through primaries and caucuses. Superdelegates are always free to support any candidate at any time, whether the candidate drops out, suspends or stays in.
National party rules say that a candidate who "drops out" keeps any district-level delegates he or she has won so far but loses any statewide delegates he or she has won.
Romney is expected to announce his decision Thursday afternoon at the annual Conservative Political Action Conference in Washington, three Republican sources told CNN