\documentclass[12pt]{amsbook}% Donald Arseneau
\usepackage[normalem]{ulem}
\RequirePackage[dvipsnames]{xcolor}
\definecolor{black}{named}{Black}

\makeatletter
\def\cshade#1{\bgroup
  \color{#1}%
  \def\UL@start{\setbox\UL@box\hbox\bgroup\everyhbox{\UL@hrest}%
    \let\UL@start\@empty \def\UL@unegroup{\bgroup\bgroup}\let\UL@leadtype\@empty
    \bgroup \color{black}%
    \kern-3sp\kern3sp % kerns so I can test for beginning of list
    \if@ignore \global\@ignorefalse \ignorespaces \fi}
  \def\UL@leadtype{%
     \leaders \hrule \@height\ht\strutbox \@depth\dp\strutbox }%
  \ULon%
}
\makeatother

\begin{document}

Would you please send in \cshade{cyan}{a short one 
par\-a\-graph re\-port saying we have some preliminary data?
Would you please send in a short one 
par\-a\-graph re\-port saying we have some preliminary} data?
Would you please send in a short one 
par\-a\-graph re\-port saying we have some preliminary data?

\end{document}