\begin{table}[htbp] 
\centering 
\caption{\bf Within-Pool Comparisons: NP-Score of State Legislators Who Run vs. Those Who Do Not (Threshold to Define Pools = 50 Percent)} 
\label{tbl_main_regressions_run_50} 
\begin{tabular}{lcccccc} 
\toprule\toprule 
& \multicolumn{3}{c}{Democrats} & \multicolumn{3}{c}{~Republicans} \\ [.05in] 
Sample                 & Coeff.  & Std. Error  &  \# Obs.  & ~~Coeff.  &  Std. Error  &  \# Obs.  \\ [.01in] 
\midrule 
All pools              & -0.023 & (0.021) & [3197] & ~~0.083 & (0.022) & [5150] \\ [.01in] 
Open seats             & 0.002 & (0.020) & [1720] & ~~0.073 & (0.021) & [2583] \\ [.01in] 
Safe districts         & -0.029 & (0.026) & [1379] & ~~0.079 & (0.029) & [2906] \\ [.01in] 
Competitive districts  & 0.005 & (0.037) & [920] & ~~0.095 & (0.029) & [1759] \\ [.01in] 
\bottomrule 
\end{tabular} 
\end{table} 
