Lukashenko, who has been in power for 26 years, was not on the EU's original list of 40 individuals targeted for travel bans and asset freezes, but the EU says his refusal to consider new elections as a way out of the crisis left it with no choice.
EU ambassadors will be given a second sanctions list of 15 officials, including Lukashenko, at a meeting on Wednesday and - barring objections by any member states by close of business on Friday - the plan will be adopted.
The sanctions aim to support mass anti-government protests in Minsk, where thousands of demonstrators have been arrested.
Belarus announced retaliatory measures against the EU last month.