HRC campaign is not threatening to sue over the Texas caucus rules - that is the last thing they want to do.  Any law suit would take weeks or longer to resolve; they don't have the luxury of that much time.  Instead, they are trying to preempt voter disenfranchisement by addressing potential problems in advance and reaching agreement with the Obama camp as to how those potential problems will be handled.  The allegation, that HRC is threatening a legal challenge is just another example of the deceptive practices of the Obama campaign - of inventing positions of the Hillary campaign in order to discredit and attack those invented positions. And the Media plays along.  

Both sides are asking for clarification of the rules, for good reason. As in previous primaries this year, there is concern that the state democratic party has not adequately planned for the expected turn out and the "rules" do not adequately address the problems that could ensue.  For example, overcrowding, long lines, not enough precinct chairs, all could lead to voter disenfranchisement.  Clarification of rules with respect to these potential problems is necessary to protect voter rights and achieve a smooth caucus.