Plaid Cymru leader Leanne Wood has condemned what she calls a "deliberate attempt to smear" the party's candidate at the centre of a Nazi slur row.
Mike Parker wrote in 2001 that parts of Wales were inhabited by "gun-toting final solution crackpots" from England.
The Ceredigion candidate said he would not use such phrases now as he was "hopefully wiser" but did not believe he had anything to apologise for.
Ms Wood backed him but said the words "final solution" were "problematic".
In her first public comments on the controversy, she said she had not been "tempted to ditch" Mr Parker over the magazine article, describing him as an "excellent" candidate.
Facing questions in a pre-arranged appearance on BBC Radio Wales' Jason Mohammad programme on Thursday, Ms Wood also said she saw a "growing racism" in Wales, particularly in "attitudes towards people of the Muslim faith".
On the row over Mr Parker's article, she said: "This is a deliberate attempt to smear Mike Parker. He is a good candidate, and he is a strong anti-racist.
"He will not apologise - there are two words ("final solution") that he would not use today.
"I'm furious with the attempts to smear Mike Parker and Plaid Cymru and to try to make out that there's some sort of negative or racist attitude on our part when what he was doing was speaking out against racism.
"It's been twisted and it's wrong."
The candidates so far declared to be standing in Ceredigion are: Henrietta Hensher (Conservative), Jack Huggins (Trade Unionist and Socialist Coalition), Gethin James (UKIP), Mike Parker (Plaid Cymru), Huw Thomas (Labour), Daniel Thompson (Green Party), and Mark Williams (Liberal Democrats).