It is not uncommon for employers to carry out a search for candidates and conduct interviews only to halt the process prior to making an offer.
Candidates may or may not be informed about why the offer has been put on hold, but reasons range from unanticipated budget concerns and unexpected restructuring to a change of heart by an incumbent about leaving the firm.
What should you do if you are given a job offer, but then are told it is on hold? First, ask the employer if there is a time frame for determining the status of the job to get an idea about when a decision might be made. During the discussion, let the company representative know that you are very interested in the job and would like to receive continued consideration.
Towards the end of the time period given by the employer, reach out to your contact at the company. If no timing has been shared wait about three weeks to follow up.
How to Follow Up
Your follow up communication should usually be an email unless the employer has suggested a phone call so that you avoid pestering your contact.
Your overture can be framed as "checking in" on the status of the search and should include an affirmative statement regarding your continuing interest. You might consider providing some new information of potential interest such as an additional certification, award or accomplishment.
It is common for job seekers who have received some positive indications that they are a preferred candidate to halt their job search activity. That's not a good idea. You should continue your active search for other jobs until you have a definitive job offer. That way, you won't lose momentum with your search since the job at hand may never materialize.