Gachagua said no amount of intimidation would deter him from campaigning for a joint opposition candidate.
The UDA wants Mr Gachagua barred from campaigning in the area, since his DCP party has no candidate.
Democracy for Citizens Party leader Rigathi Gachagua has vowed to humiliate President William Ruto and his allies in Mbeere North Constituency in the November 27 by-election, even as he alleged plans by the State to rig the polls in favour of the UDA candidate.
Addressing a roadside rally at Kanyuambora and Ichiara shopping centres in Embu County on Sunday, the former deputy president swore to camp in the area until the Democratic Party (DP) candidate, Mr Newton Kariuki, wins the by-election.