Web Forms :: Passing A Button's Click Event To A OnPreRender Method?

I'm attempting to use a Button's OnCommand method to handle it's click event so that the event is passed on to OnPreRender method as shown below. So basically the OnPreRender method is called upon a button click. I'm need to use the OnCommand method because I have 2 buttons.

//mark up
<asp:DataPager ID="GroupSearchResultPager" runat="server" OnPreRender="groupSearch_PreRender" >
<asp:Button ID="btnSearchUser" runat="server" Text="Search" OnClick="btnSearchUser_Click" CommandName="searchUser" />
//code behind
protected void btnSearchGroup_Click(object sender, CommandEventArgs e)
{
groupSearch_PreRender(this, e); //call groupSearch_PreRender
}
protected void groupSearchView_PreRender(object sender, CommandEventArgs e)
{
if(e.CommandName=="searchUser")
{
do stuff
}
}

However, this results in the following exception:

CS0123: No overload for 'groupSearch_PreRender' matches delegate 'System.EventHandler' So basically groupSearch_PreRender only takes an EventArg. I've tried casting as shown below but it doesn't seem to work. How else can I pass the button click event to the PreRender method?

protected void groupSearchView_PreRender(object sender, EventArgs e)
{
CommandEventArg entry = (CommandEventArg)e; //casting to CommandEventArg
if(entry.CommandName=="searchUser")
{
do stuff
}
}