Is it possible to apply a single style to selected text?

Hi,

If I have a text, select a style (element = "p") from the combo and I gat something like

<p>text</p>

If I select another style (element = "pre") with that text selected I get something like

<pre><p>text</p></pre>

I'd like to replace the current tag to the last selected, so only one style is applyed to the text:

<p>text</p>

becomes

<pre>text</pre>

How can I make the editor to involve in this way?

Thanks!