Protected vs. Private Variables in VB.NET....

I am setting up a global variable that will hold my string value. What is the proper use to share this variable amongst other methods within my class? Private or  Protected? Advantages vs. Disadvantages of both? This is my local variable declaration so far:
Protected connstr As String = CWSessions.GetConnString(Page, System.Configuration.ConfigurationManager.ConnectionStrings("ESQLConn").ConnectionString())  
 
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